A Revision of Anthurium Section Pachyneurium (Araceae)

317 Pages·1991·255.3 MB·English

Volume
78
Annals
Number
of the
1991
Missouri
Botanical
Garden
ANTHURIUM
A OF
REVISION
Thomas
B. Croat^
PACHYNEURIUM
SECTION
(ARACEAE)'
Abstract
Anthurium Pachyneurium
This is the first published revision of sect. since that of Engler in 1905. Section
Pachyneurium is one of 19 sections (all but one of which were treated by Engler, 1905, in his revision of Anthurium).
The section consists of 4 species representing 26 taxa in two series, series Pachyneurium Schott, and the new
1 1 1
series Multinervia Croat, with 110 and 16 taxa respectively. Forty-eight taxa (including nine subspecies or varieties)
are described as new.
Pachyneurium
Section one of 19 recognized gin rolled around the midrib and the rolled up
is
for Anthurium and perhaps the most easily rec- opposite margin (like a continuous coil in cross
is
ognizable and well-defined group in the genus. section).
It
was The
for this reason, despite size and taxonomic section consists of two series with most
its
difficulty, that this section was chosen as a starting species in series Pachyneurium. The other series,
point for a revision of the genus. Section Pachy- Multinervia, restricted to the Andes of South
is
neurium generally defined by frequently rosu- America, especially in Ecuador. Series Pachyneu-
is its
rium
late or "bird's-nest" habit, short, densely rooted contains the species originally included in
its all
caudex, the commonly short-petiolate, oblanceolate grex Pachyneurium by Schott 860), and most
1
(
to obovate, mostly coriaceous leaf blades with usu- of those included by Engler (1905) in sect. Pachy-
ally free-ending primary lateral veins and, most neurium. Series Multinervia contains species un-
importantly, the involute vernation (rolled inward known to Schott and mostly unknown to Engler.
The
from both margins) of the developing leaves (Fig. few species of series Multinervia treated by
All other sections o{ Anthurium, and indeed Engler were incorrectly placed in sect. Polyneu-
1). all
other genera of Araceae (except Lagenandra), rium or in sect. Urospadix, the latter having been
have convolute vernation (Fig. with one margin employed by Engler as a rather broad "dumping
2),
rolled inward toward the midrib and the other mar- ground." See Appendixes and 2, respectively.
1
DEB
BSR
This study was completed with support from National Science Foundation grants 80- 649 and
' 1 1
8306297. Support for publication was provided in part by National Science Foundation grant BSR-8914018.
^ P. A. Schulze, Curator of Botany, Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri 63166-0299,
U.S.A.
Ann. Missouri Box. Gard. 78: 539-855. 1991
Annals
540 of the
Garden
Missouri Botanical
when
for the ultimate disposition of species treated in refers to the color at anthesis, i.e., the spadix
when
Pachyneurium by Schott and by Engler. See producing stigmatic droplets or fresh sta-
sect. is
mens
Appendix 3 for the disposition of all currently rec- are emerging. Colors referenced in the de-
ognized Pachyneurium species and their sectional scriptions that follow are taken from the color chart
&
Kay
placement in the revisions of both Schott and En- by Berlin (1969). This is hereafter cited
&
as B K. This color chart, available from the
gler.
University of California Press, a reproduction of
is
maximum
40
the Munsell Color Array of hues, at
Methods and Materials
The B
saturation, with nine degrees of brightness.
& K
This revision was based on field studies in Central color chart represents 40 hues in the vertical
America between 1967 and 1979 and South
in columns and nine degrees of brightness the hor-
in
America in 1969 (Colombia), 1972 (Peru), 1976 izontal rows. Colors are arranged in 10 basic clus-
1984
(Colombia and Ecuador), 1980, 1983, (west- ters with four different hues per cluster, ranging
ern South America), 1984 (Venezuela), and 1986 from red through yellow, green, blue, purple, and
(western South America and but 28 of The columns each
Brazil). All finally red-purple. four for color
the 125 taxa were studied live or are under cul- cluster are numbered 2.5, 5, 7.5, and 10. These
tivation at the Missouri Botanical Garden. Except numbers are repeated for each basic color type.
& K
for those so indicated, all descriptions can be as- The colors from the B color chart are read
sumed to have been prepared from both living and by reporting the color, then the row followed
first
dried material. Morphological characters were cod- by the column. For example, the third color the
in
ed directly into a computerized database to ensure row in the red area would be called Red 5/7,5,
fifth
The
and The
parallel sortable descriptions. aroid de- second color in the eighth row would be called
228
scriptions database contains characters that Red 8/5.
are used to describe the morphological diversity estimates of ecological zones given
All in this
exp ^ed by Anlhurium. The database also pro- paper are based on either Holdridge Life Zone maps
vides a means of sorting species by characters for for most Central American countries and for Pan-
ama
writing keys, as well as for compiling lists of various or on the ''Mapa de tipos de vegetacion de
character states. In addition, the database can be la Republica Mexicana'' (Flores et ah, 1971). As
put to future use for identifications and for additions yet no study has been made to correlate the veg-
new The map
of species for other treatments. description etation types represented on the Mexican with
file is directly tied to a nomenclatural database those of the Holdridge Life Zone system. For an
names and
containing all species publication data understanding of the latter system, see Holdridge
for all Araceae species stored in Tropicos (Crosby, (1971). For South America, maps based on
et al.
&
Each
1986; Crosby Magill, 1986). species is the Holdridge System were used for Bolivia, Co-
represented by a unique number, which ties to lombia, Ecuador, Peru, and Venezuela,
it
data in other files associated with the species. Dis- Mention should be made of the distribution of
cussions and exsiccatae are also stored in separate herbarium material of Araceae under cuhivation.
files, as are synonyms, but all parts are automat- Herbarium material may consist of one of three
ically reassembled for the final treatment. Herbar- kinds: (1) fertile original (wild) collections; (2) sterile
ium specimens can be added to the exsiccatae original collections with an inflorescence added from
database any time and sorted a standardized same number
at in the cultivated plant of the (generally
manner
before being printed out. Thus, exsiccatae same from which specimens
the individual the
field
records can be added up to the last moment, even were made); and material collected entirely
(3)
when
the manuscript has been completed. Species from Specimens based
the cultivated plant. entirely
decoded
descriptions are into narrative text auto- or in part on cuhivated material are clearly indi-
matically from the descriptor base and require only cated as such in herbaria,
minor editing to put them in a publishable form.
may
Final treatments be saved on hard disk or
Acknowledgments
stored on tape, but the coded description data (which
use very core storage space) are a part of the acknowledge the assistance of numerous hor-
little I
who
permanent Tropicos database and can be used for ticulturists provided living material, especially
M.
other projects such as floras or ecological studies, R. Birdsey, C. McDaniel, Williford, R. Burle-
J.
The terminology and usage the descriptions Marx, S. Mayo, M. Carmichael, Brenner, S.
in
J.
&
inthispaper are defined by Croat Bunting (1979). Thompson, F. Fuchs, and T. Fennell, and to
Jr.,
The color of the spadix, unless otherwise indicated, others who provided observations on leaf vernation
Volume Number
3
78, Croat
541
1991
Anthurium Pachyneurium
sect.
and fruit color, namely Banta, C. Fleming, M. rium were described in the genus Pothos: Pothos
J.
Grayum,
H. and
R. ShefFer. R. Sheffer also has crassinervia was described by Jacquin 1793
in
by
assisted greatly studying the cytology and breed- and transferred Anthurium by Schott 1832.
to in
ing behavior of Pachyneurium at the University The other two were Pothos solitarius Veil. Cone,
of Indiana Northwest. I thank the following insti- described in 1829, and P. maxima Desf., described
me
tutions, which loaned or allowed study 1832. The former was Anthurium
to their in transferred
to
AAU, BH, BM,
specimens: A, B, BR, C, CAS, by Schott Prorfromw5(
in his 1860), while the latter
CAY, CHAPA, CM, COL, CR, DUKE, ECON,
was transferred Anthurium by Engler 1905
to in
ENCB, F, FTG, G, GB, GH, GUA, HUA, IAN, and here treated as a nomen dubium owing
is to
IBE, INPA, ITIC, K, LAM, LL, M, MEDEL, the inability to place with certainty in any cur-
it
MEXU,
MG, MICH, MY, NY, PMA, QCA,
The
P, rently recognized species. genus Pothos as
QCNE,
R, RB, S, SEL, SI, TEX, U, UC, UCLA, now circumscribed restricted to Africa and Asia,
is
UFMG,
UB, US, USM, VEN, W, WIS, WAG, Modern
especially Southeast Asia. suprageneric
XAL.
Also acknowledged are reviewers D. H. do Pothos An-
Nic- classifications not place close to
olson and M. H. Grayum, especially the extensive thurium. Grayum (1984) places a separate
in
it
work with the manuscript by Grayum. I also thank tribe, Potheae in the subfamily Pothoideae. Gray-
um
Nicolson Anthurium
for his considerable help with thorny no- considers isolated but closer to Po-
menclatural problems with Pachyneurium. thos than to any other genus. He places Anthurium
Special credit goes to volunteer workers, in- in a separate tribe Anthurieae in the same subfam-
&
cluding A. E. Westhoff and Patricia Croat, for ily. Bogner Nicolson (in press) remove Anthur-
preparation of Latin descriptions, and to the latter ium from the Pothoideae altogether and place
it
Kay Rossmann
for final editing; to for typing and in the subfamily Lasiodeae, leaving Pothos in the
editing all parts except the descriptions and exsic- Pothoideae with only two other closely related gen-
Edwina Medlock
catae; to for a two-year pheno- era, Pedicellarum and Pothoidium.
logical study of leaf, flower, and fruit production The epithet Pachyneurium was first used in
and for her cross-pollination program; to my tech- 1860 by H. W. Schott in his revision of the
first
nical staff for assisting with the project, including Araceae Prodromus Systematis Aroidearum,
in
past research assistants Frances Mazanec (1980- Although no Anthurium species were treated
in
1985) and Honora Murphy (1986); to the green- his earlier Synopsis Aroidearum in 1856, 20 spe-
house Petra Malesevich and Mary Nyswon- were Prodromus,
staff, cies treated in the Half of these
ger, for answering repeated queries, transporting were described by Schott himself that work or
in
myriad
a of plants to the office, pollinating plants, in earlier works during the previous decade. Others
harvesting fruits, and keeping records on pheno- were described by Karl Koch or Frederick Lieb-
logical changes; and to Rob Wilds and Dan Mount mann during the same decade. In addition to the
for participating in the pollination program. four species described as Pothos mentioned above,
my
Most special thanks to current research as- only one species of sect. Pachyneurium, A, cras-
who me
sistants, helped bring the project to com- sinervium {Jacq.) Schott {descrihed as Pothos cras-
Anna was
pletion: to Brzyski for describing plants, en- sinervia in 1793), described before the early
tering descriptions, and assembling the 1850s. Three of the 20 names included Schott's
final in
manuscript for descriptions, exsiccatae and species 1860 revision, namely A. acaule (Jacq.) Schott,
Harmon Kunth aduncum
excluded; Dylan phases A, hookeri and A, Cone.)
to for assisting in (Veil.
all
1850
of the project, especially generating the South Schott, were published before but these have
in
American species key, assembling and been excluded from Pachyneurium and placed
illustrations in
final editing, and to Petra Malesevich, who assisted other sections (see Appendix
1).
The Of Pachyneurium names
in the final editing process. revision could not the remaining in
have been finished without the able assistance of Schott's 1860 revision, only nine species remain,
&
these dedicated staff and volunteers. These include A. wagenerianum K. Koch
Bouche, A. fendleri Schott, A. spectabile Schott,
A, crassinervium (Jacq.) Schott, A. Schott,
ajffine
History of Section Pachyneurium
Kunth, crenatum Kunth
A. schlechtendalii A.
(L.)
The Pachyneurium
species of sect. as (erroneously treated by both Schott and Engler as
first it is
recognized here was described by Linnaeus (1763) A, acaule (Jacq.) Schott (Mayo, 1982)), A. dom-
in Species Plantarum as Pothos crenata, and was beyanum Brongn. ex Schott, and A. solitarium
transferred to /i/i//tuau/7i by Kunth in 1841. Three (Veil. Cone.) Schott. other species of
Still sect.
other species clearly belonging to sect. Pachyneu- Pachyneurium were described in Schott's revision,
542 Annals of the
Garden
Missouri Botanical
but these he included in other groups (termed A, leonianum Sodiro
"greges" by Schott). These included A, protensum A. acutifolium Engl.
Schott (included grex Ery thropodium)^ A. oxy- A, latissimum Engl.
in
pum
Poeppig and A. consobrinum Schott (grex A. barclayanum Engl.
Oxycarpium)^ and A. oerstedianum Schott (in- A, ernestii Engl.
Hemsley
A. salviniae
difc
grex XialophyIlium, Thus, a total of 13 species A. llndmanianum Engl.
&
of Pachyneurium were included in Schott's revi- A, martianum K. Koch Kolb
Koch
even though some were not recognized as A, selloum K.
sion,
such. A. pallatangense Engl,
1905 62 names were A. linguifolium Engl.
In Engler's revision,
in-
Pachy-
Pachyneurium (Appendix Of Until recent times, relatively few taxa of
eluded
in sect, 2).
18 were Pachyneu- rteuriwm had been described subsequent to Engler's
only species actual
this total,
A names
revision. of the published subsequent
rium species not already included in Schott's re- list
Fourteen of the names included by Engler to Engler's time and prior to the beginning of this
vision.
work
12 two were presented here:
(in reality only species, since syn- is
onyms), includine A. hookeri Kunth, A. hacu- c d
j- = j
j a dombleyanum
^- cigoyanense bodiro A. brongn.
. . , 1 •
mense weberbJaueri T-» and
Engl., A. Engl., species
all
ex Schott
numbered 52 through 62, have subsequently been
=
dombeyanum
agoyanense
(1905) A.
var.
proven be non- Pachyneurium Appendix
to (see
2).
Brongn.
Ten names included by Engler were synonyms of =
dom-
eleutheroneuron Sodiro (1905) A.
var.
names names
earlier in Schott's revision, three
beyanum
Brongn.
synonyms names own
were of older Engler's ^
in
aagustilaminatum
Engl.
and names have been excluded
revision four be- =
albidum angustilam-
var. Sodiro (1906) A.
cause of confusion in the nomenclature (see Species
inatum
Engl,
maximum
Excluded section). These are A. (Desf.) =
var. brevipes Sodiro (1906) A, angustilam-
&
Engl., A, cymatophyllum K. Koch Sellow, A.
inatum
Engl,
agnatum
and tricarinatum
Schott, A. Sodiro. =
crassum angustilam-
var. Sodiro (1906) A.
In addition to the 18 species that Engler added
inatum
Engl,
to those Schott had included in his grex Pachy- =
gladiatum Sodiro (1906) A. angusti-
var.
neurium, Engler included the following elsewhere:
laminatum
Engl.
oxycarpum Oxjcarpium),
A. (sect. A. pallatan- ^ &
atropurpureum Maguire
R. Schultes
gense Engl. Polyneurium)^ A. oerstedianum
(sect.
atropurpureum
(1953)
var.
Schott (including A. cuspidifolium Schott, in sect. =
apertum
var. R. Schultes (1954) A. bon-
Urospadixy series Obscureviridia\ A, linguifolium &
plandii R. Schultes Maguire subsp, bon-
Engl, (sect, UrospadiXy series Flavescentiviridia)^
plandii
and A. spathiphyllum N. ^
E. Br. (sect. Episeio-
tonplandii Bunting (1975)
stenmm). Of these, only A. pallatangense and A. ^
concolor K. Krause (1932)
had been by
linguifolium not treated Schott.
f<
Thus
the 45 years between the publication ^ =
in
giganteum Matuda (1950) A. salviniae
1860
of Schott's revision in and Engler's treatment
Hemsley
Das
Pflanzenreich 1905, an 22
for in additional
Bunt A. bonplandii
were
valid species described, bringing the
total
guayanum
Bunting subsp. (Bunting) Croat
number Pachyneurium The
of ^
species to 33. spe- &
lanjouwii Jonker Jonker (1966)
ces mcluded by Engler, but not by Schott, the ^
in
Hawkes
^agairei A. (1948)
present concept of sect. Pachyneurium were as ^
^^^^^.^ ^^^^^^ ^^32)
j^
follows (in the order presented in the revision): =
Hawkes paraguayense
A. rodrigoi A. (1948) A.
Engl.
A, pendulifolium N.
E. Br.
A. superbum Madison (1978)
paraguayense
A.
Engl.
=
A. tessmannii K. Krause (1932) A. uleanum
joseanum
A. (= protensum
Engl. A, Schott)
Engl.
A. jenmanii
Engl.
A. wurdackii Bunting (1975)
uleanum
A.
Engl.
A, tarapotense Engl. Of the 21 names listed above, 10 represent
still
A. cubense Engl. valid taxa, while the remainder have here been
Volume Number
3
78, Croat 543
1991 Anthurium Pachyneurium
sect.
46 number
synonymized. This raises to the of taxa prevalent in areas where there a pronounced dry
is
Pachyneurium
of sect. at the time this researcher season, especially in areas of tropical moist
forest,
began working with the Araceae (in approximately While species in sect. Pachyneurium occur in most
1976). Subsequent to 1976, an additional 16 spe- life zones, most occur in tropical dry, premontane
Pachyneurium
cies of sect. have been described. dry, and tropical moist forest. Relatively few spe-
In "The Genus Anthurium (Araceae) in Costa cies occur in tropical wet, premontane wet, or
&
No
Rica," Croat R. A. Baker (1979) described six montane wet forest life zones. Pachyneurium
known
additional species: A. brenesii^ A. prolatum^ A. species is from pluvial tropical forest.
schottianum, A. seihertii, A. standleyi, and A. In habit, especially in terms of their short stems.
Two
more
upalaense. species were described in short, densely rooted internodes and mostly erect
preparation for a revision of Anthurium for Pan- leaves held in a tight rosette, Pachyneurium spe-
aima^nameiy A. luteynii and A. purpureospathum resemble most
cies closely species of sect. Por-
(Croat, 1981); two species. A, halmoorei and A. phyrochitonium. Indeed, some members of that
salvadorense^ were described in ''A Revision of section, for example Anthurium hacumense Engl,
the genus ^n^Aurium for Mexico and Middle Amer- (placed in sect. Pachyneurium by Engler), are
ica" (Croat, 1983) and two more, A. nervatum often confused with Pachyneurium
(Fig.
5). Still,
"A
and A, pseudospectahile^ were described in species of Porphyrochitonium differ by having
Anthurium Panama"
Revision of the of (Croat, dark glandular punctations on one both
or leaf
number
1986). In addition, a of Venezuelan species surfaces, and in having convolute, not involute,
have been described by Bunting (1986, 1988, vernation and berries which are often depressed
1989) since this project began. These include A. apically with two or more seeds per locule. In
xanthoneurum and A. quanchezii (1986), A, addition, sect. Porphyrochitonium ecologically
vi-
is
nillense (1988, along with three others introduced very different, inhabiting some of the wettest
life
into synonymy), and A. iramirezae (1989). Fi- zones such as pluvial rainforest. The Choco region
nally, one species, A. plowmanii, was described of Colombia, for example, which one of the
is
during the preparation of the treatment of the wettest places on earth with more than 500 inches
mm)
Araceae for the "Flora de Paraguay" (Croat, 1987). (2,272 of rainfall per year, the center of
is
The current work includes a total of 114 species, diversity for sect. Porphyrochitonium. Possibly
126 48 member
representing taxa, of those being described also a of sect. Porphyrochitonium An-
is
147%
for the first time. This is more species than thurium hookeri Kunth, which resembles sect.
were recognized at the outset of the work. Pachyneurium more than any other non- Pachy-
neurium from Porphy-
(Fig. 6). It differs typical
much
rochitonium in being larger and in having
Within Anthurium
Sectional Relationships
scalariform secondary lateral veins and perhaps
Pachyneurium
Section one of 18 sections
is belongs in a section of own.
its
recognized by Engler (1905). While Schott (1860) Much more easily confused with Pachy-
sect.
recognized 28 groups (and this probably will prove neurium than Porphyrochitonium
sect. a
rel-
is
number
to be closer than Engler to the actual of atively small group of species which also has the
needed sections in Anthurium)^ he was dealing with bC bird's-nest" habit and shares similar oblong to
known
only a small percentage of the species to
oblanceolate or obovate leaf blades, but without
Engler. Engler no doubt found it necessary to involute vernation (a feature considered an absolute
broaden the concepts of the subgeneric groups
in requirement regardless of habit or blade shape),
new
order to include all the species. In doing so, Typical of group A. michelii
this Guill. (Fig.
is 3),
some
groups lost definition. This is particularly true once considered to be a member of Pachyneurium
in the case of the species he placed in sections (Croat, 1983). These species, with epunctate, ob-
Belolonchium, Urospadix, Polyphyllium, and
and
lanceolate to oblong-elliptic blades generally
XialophyIlium, all of which (and especially the short stems with short internodes are mostly small
first) contain what appears to be a wide variety of plants not easily confused with typical Pachyneu-
A
seemingly unrelated species. discussion of these rium species, but some of the larger ones, such as
and some
groups, proposals
their typification, for mic^e/u, are in fact easily confused with Pac/ij-
/4.
realignment will be the topic of a future paper. neurium. This group of plants has not been placed
Pachyneurium
Section is distinct in its ecolog- with certainty in any group, though tentatively
it is
requirements and the most edaphically adapt- new
ical is placed in a section including A. decurrens
ed of all the sections to xeric growing conditions. Poeppig, placed by Schott (1860) in his grex Ox-
Because most
of this, the taxa in the section are ycarpium. Since only three species, A, decurrens
544 Annals the
of
Garden
Missouri Botanical
Poeppig, A. oxycarpum Poeppig, and A, conso- rium has independently evolved the cordate con-
brinum Schott were included Schott's grex Ox- dition rather than having independently acquired
in
ycarpium, and since the two latter species are now involute vernation. The reasoning here is that leaf
placed Pachyneurium (along with the ep- vernation a conservative ontogenetic character
in sect. is
Oxycarpium, which now synonymous whereas leaf blade shape in the genus a highly
ithet sect. is
is
may
with sect. Pachyneurium) only A. decurrens re- plastic one. Indeed, leaf shape be highly vari-
The name new even on on
malns. for this section will be pro- able individual plants (see section leaf
posed in a future paper. This new section the blades under Morphology).
is
only section (other than sect. Urospadix) with short The Central American species of Anthurium are
now
internodes and elongate, epunctate leaf blades with well known, and suspected species have
all
convolute vernation. Section Urospadix be- been screened for the presence or absence of in-
is, I
endemic
lieve, distinct from the latter section based on gen- volute vernation. Despite the fact that the
erally closer, more uniform primary lateral veins South American Pachyneurium species are less
many
and more restricted geographical distribution, well known, cordate South American species
its
have been and no Pachy-
mostly in southeastern Brazil. studied in cultivation,
among
Section Urospadix (Fig. 4) the next most neurium species have been found them,
is
Pachyneurium. Thus phenomenon
group be confused with the of subcordate- or cordate-
likely to
Pac/ij^eurm^
These two are probably not closely related owing leaved seems to be largely a Central
American and West
to their lack of involute vernation (although one Indian one. It is in these regions
probable species of sect. Urospadix has hybridized where some cordate Anthurium species with short
—
Pachyneurium and
with a see section on breeding stems, short internodes blades with free-ending
common many
behavior). Given that this character state, a con- veins (a relatively feature in cor-
servative ontogenetic feature, present only in date-leaved Anthurium) might be confused with
is
sect. Pachyneurium and in only one other genus sect. Pachyneurium. Engler placed a number of
Pachyneurium
in the family, Lagenandra, seems apparent that these species in his sect. (Appendix
it
Pachyneurium has no close relatives. Nev- These included A. longispathum Carriere
2).
:t.
(
many
ertheless, sect. Urospadix has features in A. grandifolium)^ A. grandifolium (Jacq.) Kunth,
common boucheanum Koch
Pachyneurium, A. K. (= A. cartilagineum
with especially the short
stems, close internodes, frequently rosulate habit (Desf.) Kunth), A. liebmannii Schott (= A, um-
umbrosum
and the presence of elongate, often short-petiolate brosum Liebm.), A, Liebm., A. cor-
datum
leaf blades. In gross morphology they differ from (Willd.) G. Don, A, andicola Liebm., A.
members of series Pachyneurium in their generally cartilagineum (Desf.) Kunth, A. hrownii Masters,
appunianum
spaced and moderately obscure primary A, Schott (= A. cartilagineum)^ and
closely
lateral veins. Some members of sect. Urospadix A, seleri Engl. Except for A. seleri, most have
many
members Pachyneu-
are very similar to of series Multinervittj of the general features of sect.
many
a group mostly restricted to the Ecuadorian Andes. rium and are in ways similar to Central
From American and West
species of series Mu/^trterfta they differ prin- Indies cordate-leaved species
cipally in having supervolute vernation, and in be- of Pachyneurium, except that they lack involute
ing geographically isolated in the geologically more vernation. Thus, not surprising that Engler,
it is
ancient parts of eastern South America, namely apparently unaware of the important character of
Brazil. Section Urospadix ranges principally from involute vs. supervolute vernation, placed these
On
Pachyneurium.
the state of Bahia to Sao Paulo with at least two species in sect. the other hand,
outlying species (tentatively placed in this section), using general characters such as leaf shape, short
many
and
one the Venezuelan highlands {A. yutajense stems, short internodes alone, additional
in
West
Bunting) and one from the Cordillera de Costa species from the Indies, Central and South
la
{A, lilacinum Bunting). America might well have been placed by him in
Some
other groups of Anthurium, especially sect, Pachyneurium.
species currently placed in sect. Belolonchium in In general, South American species are either
Central America and in the West Indies, have not subcordate-leaved, or their blades are decidedly
species that are similar to those few species of elongate with merely the bases being subcordate
Pachyneurium
with cordate or subcordate blades, (e.g., A. fendleri).
e.g., A. venosum, A. ranchoanum, A. schottian- The remaining sections of Anthurium are not
um, A. standleyi, A. colonicum, and A. colobrusii. at similar to members of Pachyneurium and
all
It believed that this latter group of Pachyneu- need not be discussed.
is
Volume Number
78, 3 Croat 545
1991 Anthurium Pachyneurium
sect.
Morphology
of Vegetative Structures
especially the size of the petiole bases, the stem
^„_„ diameter highly irregular from node to node with
is
growth -1,
patterns
.
the petiole bases conspicuously swollen while the
The Anthurium
shoot organization of sect. very narrow intervening areas between them are
Pachyneurium Ray
has been characterized by devoted and The
entirely to cataphylls roots. ab-
Though
1 986, 1 987, 1 988). appearing un- scission scar of the petiole is generally broader than
(
branched, the stems of most anthuriums are in fact high broadest laterally, perpendicular to the
(i.e.,
highly branched with a growth pattern described axis), though the shapes of the scars are usually
as triphyllous sympodial (Ray, 1988). Each article not as variable throughout the section as the
is
segment)
(or of the shoot includes a sylleptic pro- range of variation of petiole cross sections. Petiole
phyll (P) and mesophyll (E) (both of which are abscission scars are generally rounded abaxially
cataphylls) as well as a sympodial leaf (S) (a foliage and broadly rounded adaxially. The abscission scar
and
leaf) a solitary, terminal inflorescence Veg- typically inclined inward to the axis at an angle
(I). is
110-140°
etative buds are formed only on the sympodial of from the axis of the stem. Unlike
many
segment and on the peduncle base (which Anthurium
axillary species with longer internodes,
is
to the mesophyll and the foliage leaf). This growth Pachyneurium has leaf scars that are usually not
pattern can be summarized as follows (after Ray, easily visible but remain obscured by the persistent
and
loc. cit.). cataphyll fibers roots (Fig.
7).
The Pachyneurium
stems of are generally
short,
cm
"^ usually less than 20 long, and rarely more than
cm
30 long except in very large old plants. Stem
y
cm
diameter varies from as as 1.5 in some
little
cm
of the smaller species about 7 diam. the
to in
— — —
3-4 cm
{P E S larger species, generally averaging diam.
1}
Stem
diameter in part also a matter of age, but
is
f,
mostly increases only slightly during the of the
life
plant.
* Usually the oldest part of the stem rots away
except for that portion contained in the living root
Tom
Ray
Studies by (pers. comm.) have defined mass. Older parts of the stem are frequently
at-
the shoot organizations and growth patterns. In tacked by root borers, which enter through the
this
Pachyneurium
regard sect. is identical to that of softer central portion of the stem and bore up into
all species of ^rt//iurmm with the exception of sect. the younger portions. However, perhaps because
Polyphyllium. It is the sylleptic prophyll which of the seasonally dry habitats and the generally
is
termed the cataphyll throughout this work and massive root ball, which provides protection to the
previous works by this author on Anthurium (Croat, stem, sect. Pachyneurium exhibits fewer cases of
The
1983, 1986). stem thus consists of a series infestation by root borers than perhaps any other
of units (articles), each of which comprises a branch section of Anthurium.
\
with a single foliage leaf subtending (eventually) a Only rarely do Pachyneurium species have no-
continuation shoot and a terminal inflorescence. ticeably elongate internodes. Some species, such
as A. consobrinum, tend to grow rapidly when
young, producing internodes to several centimeters
STEMS
long, before reverting to a slower growth with short,
The stems Anthurium Pachyneurium broad Some may
of sect. internodes. species revert to a
are characterized primarily by being generally short growth pattern with slightly longer internodes when
and densely rooted. While most members of other disturbed or dislodged from their positions in trees,
sections of Anthurium (excluding Xialophyllium especially when they land on their sides or land
and Tetraspermium) have short to moderately short upside down. This reversion to longer internodes,
common
internodes as well, few sections ever have species so in other genera and even in other
common
with such extremely short internodes. Typically, sections of Anthurium^ not Pachy-
in
is
those of sect. Pachyneurium are several times neurium, and even when reversion to production
broader than long. Moreover, the caudex differs in of longer internodes does occur, the duration of
much
more
being densely rooted than other long internode production always very
in brief.
is
Depending on stem and Of two Pachyneurium^ Mul-
sections. the size of the the series of series
Annals
546 of the
Garden
Missouri Botanical
4
tinervia has a stronger tendency to produce longer into the basket often formed by the rosulate habit
The
internodes. This no doubt owes to their generally and the short-petiolate leaves (Figs. 7, 8» 14).
more mesic habitats at higher elevations, where uppermost roots are the most active in terms of
more compact stems have advan- growth, and generally act as feeder roots.
the closer, less
tage (and perhaps some disadvantage since the Even in such situations, other roots, usually
still
more typical plants in series Pachyneurium would those further down on the stem, act more for an-
probably become waterlogged and such chorage and support. These are also generally lon-
rot in cool-
wetter environments). ger, stouter, and less well ordered, being instead
er,
Pachyneurium stems are tough and moderately more frequently intertwined. They are nevertheless
and
perhaps owing to the presence of nu- equally capable of entrapping debris are, at
inflexible,
merous coarse Only the central or older least near the periphery of the living root mass,
fibers.
parts of the stem are offering one of the few debris-infested. Because long-petiolate species are
soft,
avenues for predation (the other being through the less likely to be efficient at catching debris, they
area of the abscission scar where the old pe- are more likely to have their roots directed down-
soft
duncles have rotted away). ward rather than upward (Fig.
9).
Pachyneurium stems are typically erect, wheth- The root masses of most species are extremely
er habit terrestrial or epiphytic. In a few rare compact, the roots generally being completely con-
is
may
cases stems be repent, A. lindman- tiguous with one another near the surface of the
e.g., in
Pachyneurium
ianum. This presumably an ecological adapta- stem in most species of series (Fig.
is
Some many members
means
tion, providing the plant with a better of 10). species, especially of
s\xv\\\a\. Anthuriumlindmanianumus>\xdi][y occMYs series Multinervia, have less densely aggregated
in seasonally dry areas as a terrestrial plant along roots. This compact nature of the root system not
the edges of watercourses. In cultivation, the spe- only enables the plant to adapt well to dry condi-
cies will grow well in a standing pool of water on tions, allowing to absorb quickly virtually all of
it
rocks or bricks above the water level. Its roots the rainwater that passes through in brief rain
extend into the water and the typical rosulate habit showers, but also effective in keeping phytoph-
is
maintained because the petioles are turned agous insects, especially root borers, away from
is still
sharply at right angles to the stem and are held the stem.
Pachyneurium
Other
erect. species, especially the ter-
have
Despite the obvious ecological advantage of re- restrial ones, frequently their roots directed
pent stems in drier areas, this habit has not evolved downward along the stem and into the ground,
frequently Pachyneurium, More commonly, even These species, despite the fact that they too often
in
have
in extremely dry habitats, the stem and leaves are the typical rosulate habit with short stems,
are frequently growing under conditions where they
erect.
stiffly
Stems may be horizontal to almost pendent in are less likely to accumulate debris from falling
which grows suspended from leaves, and often grow out the open or
^. />5euc?o5/)6c;a6t7e, etc., in
a few roots. Potted plants of this species may grow under low forest, which does not yield such high
Some
in a curve until the apex again directed more or quantities of debris. terrestrial species, such
is
atropurpureum atropurpureum,
downward. as A. var. A.
less
pachylaminum, or A. bonplandii, often occur on
white sand soils, which are notoriously poor in
ROOTS
nutrients, and are either found growing in open
Perhaps more than any other section, Pachy- areas or growing beneath typically evergreen trees
neurium shows considerable variability in root dis- on white sand soils. In such situations, roots di-
position. Depending on the habitat and the species, rected into the soil appear to be an adaptation to
may
some species, especially short-petiolate ones, take better advantage of nutrients present in the
produce most of their roots so that they are directed soil, which might not be available from accumulated
On
upward downward some
or or spreading. Typically, in debris. species, e.g., A. linguifolium^
epiphytic species in mesic habitats that experience from a very arid area, the uppermost feeder roots
much
a pronounced dry season, at least the uppermost are reduced and directed upward rather than
upward and downard.
roots are directed are frequently nar-
mm
3-8
The
rowed and pointed at the ends as well (Fig. 8). This roots themselves, usually diam..
provides a clear advantage for collecting falling are initially covered with a dense layer of root
debris and precipitation around the roots (Figs. 7, hairs, so dense as to appear as a smooth and con-
13), These uppermost roots frequently even grow tinuous layer. Artificial drying of the stems, which
Volume Number
3
78.
Croat
547
1991
Anthurium
Pachyneurium
sect.
roots and root among
reveals their true nature, wherein the roots gen- in the section, e.g., A, loretense.
appear
erally woolly-pubescent. At one Fresh Anthurium
least ex- cataphylls of are uniformly
ception to the typically smooth roots on fresh plants green (unlike Philodendron, where may
they be
seen A. johnsoniae, which
is in has fresh roots colorful), and except for length and shape they are
with a somewhat irregular warty surface.
similar
In addition to obvious functional differences, the promptly after the emergence of each new and
leaf
have
roots taxonomic
importance, especially the thus usually no more than one
fresh cataphyll
is
color, thickness, degree of spreading, and length visible. The old, dried cataphylls are more
signif-
of the uppermost feeding roots. icant taxonomically, perhaps more
characteristic
than
those of other sections of the genus. Although
some
species, A, eximium, A.
e.g.. luteynli, A.
CATAPHYLLS
upalaense, and
A. have
willifordu cataphylls that
The
cataphyll a modified leaf that protects dry persistent and most
is intact, persist in a weath-
the newly emerging termed ered The
leaf. It is the sylleptic state (Fig. 12). degree to which weath-
Wh
Ray
prophyll by (1986, 1987, Once
1988). the ering takes place varies
substantially,
leaf emerges, the cataphyll has no functional weather to disorganized and inconspicuous
sig- fibers
nificance in remaining photosynthetic ecolog- that are mostly obscured by and
(for the roots petiole
ical significance see below) and promptly bases
dries up. (Fig. 14), other species, especially those with
Though
Anthurium
the cataphylls of do not con- longer cataphylls, dry with an
their fibers in or-
many
tribute as useful characters as do those of ganized or semiorganized
intact fashion, A.
e.g.,
Philodendron,
the cataphyll Pachyneu-
in sect.
dulifc
rium more
is diverse than in any other section of others dry intact, and then quickly weather
to fibers
Anthurium. There
are two
basic types of cata- (Fig. 19). In addition to the length of the cataphyll,
one may
phylls, with type subdivided: which vary from 3 40 cm,
to there are
dif-
ferences of color and thickness, which are taxonom-
cucuUate
(hood-shaped)
(1) (Figs. 15, 46)
many
ically significant. Unfortunately, like other
narrowly
(2) triangular or lanceolate
characters Pachyneurium,
in these differences are
(a) straight (Fig. 11)
difficult to quantify as key characters.
hook-shaped
(b) (Fig. 16).
Though
of minor importance
taxonomically,
The
former known
type rare, for certain only cataphylls have an important function
is ecologically.
in A. salviniae and A. harclayanum. They generally weather
It is inter- into fibers which, in con-
esting to note that the cucuUate cataphylls (and junction with the roots, aid in entrapping debris,
sometimes
hook-shaped
also cataphylls, A,
e.g.,
loretense) also have leaves which are
circinate
in
LEAVES
bud
in addition to having involute vernation
(Fig.
Upon
young
17). unrolling, the leaf first unrolls Petioles, The petioles of sect. Pachyneurium are
lengthwise, then unrolls toward both margins much
in the typically shorter than the blades and
this,
manner
usual of Pachyneurium.
sect. coupled with the short internodes, provides
the
The
second
cataphyll type, narrowly triangular basic ingredient the and
for rosulate habit
''bird's-
or lanceolate, overwhelmingly more common, Some
is nest" appearance. species of Pac/ijneurmm,
and most
of these are straight and erect. In South even the more typical members of Pachy-
series
America some
have may
species narrowly triangular neurium, have long petioles, but they are
less
cataphylls that are hooked phenomenon
(the effective as debris catchers and even tend have
is to
among
absent American
Central
species). Plants leaves spreading
laterally, e.g., A. llewelynii, or
with typically hook-shaped cataphylls have pendent,
also e.g., A. pendulifolium, A. pseudospec-
sharplyD-shaped
petioles in cross section (Fig. 16). tahile, and A. spectabile.
Blades emerge same
in the fashion in both types Petiole cross-sectional shapes of Pachy-
sect.
of narrowly
triangular cataphylls, but the hook- neurium are diverse, perhaps more so than any
in
shaped
type are usually smaller than the straight other section of Anthurium, Pachyneurium
spe-
ones and thus the emerging leaf usually smaller have some
is cies at least of the cross-sectional shapes
before expansion. Nevertheless, the overall size of in each category from A through E (Fig. 2 Cross-
).
1
the fully expanded leaf blade does not seem to sectional shapes in Pachyneurium are mostly "D-
correlate with the size of the newly emergent but shaped" (category B), ''markedly angular" (D) and
unfolded some
leaf blade, since species with hook- ''markedly
ribbed adaxially" (E) with fewer species
548 Annals the
of
Garden
Missouri Botanical
blade shape with blades
having petiole cross sections in category A, ''te- is actually quite variable in
The U-shaped shape rare ranging from linear-oblong to ovate-triangular to
cross-sectional
rete." is
Pachyneurium. Many species of Pachy- ovate, with bases acute to subcordate or cordate.
in sect.
The such A, schottianiim,
neurium have C-shaped petioles (A 6-8), and pet- less typical species, as
have mod-
and watermaliense,
more A. standleyi, A.
shapes that are or less trapezoidal to
iole
D-shaped with prominent abaxial ribs are especially erately thin blades with distinct posterior lobes,
more broad-
common Typically, blades are or less elongate,
(E 1-3).
The sheathed or above the middle of the blade and gradually
petiole base usually briefly (Figs. est at
is
ends
14, 16) and encircles the inflorescence (the latter tapered to the base, but frequently the blade
even
may The inconspicuous abruptly and often rounded at the base or
sheath usually
abort). is
is
much
and short, only rarely extending up to as as
fi
cm obovate shape. Leaf blades
8 long. In most cases the sheath restricted oblanceolate or overall
Is
to a very small percentage of the total length of may be quite variable at the base, even on the
the petiole but may, for example in A. consohri- same plant varying from shallowly cordate to acute
harlingianum, have
(Fig. 20).
fi
While
sheaths that extend almost to the base of the blade.
The petiole in all Pac/ijneurtum species terminates extends to the base of the midrib and ends im-
some
in a conspicuously swollen geniculum, which fa- mediately above the geniculum of the petiole,
com-
leaf blade orientation. species have a large section of the midrib
cilitates
— pletely naked, so that appears to be a part of
it
The
Blades. Vernation nature of the devel-
,,,.,.,,.
proper. This perhaps most extreme
the petiole
„ is
.^
opme .
blade hiehly significant taxonomically, es- /
is ,. ^u • u ^
^ . ^- oerstedianum, ibut. other species, such as A.
in
^^,
1 1 1 1 . 1 r
pecially at the sectional level in the case ol sect.
^ j a *•
^ guanchei zii, A. pranceanum, and\ A. remotigenic• -
n
Anthunum Pachyneun- um
Pachyneurium. J
sect.
^^^^
^^^^^^ ^^^^ ^j^.^ ^^^^^^^ ^^^^ ^^^^^^^
Anthurium known have
the only section of to
is -. j
^ ^, ir,i. , ., . some taxonomi•c vali ue, * does not* ali ways
exhibits
it
,
.
involute vernation of the developing leaf blades.
represent a character warranting specific recog-
Indeed, only one other eenus the Araceae, las:-
in .. ^
? nition. Tt.h.i.s . ^true, ^for examplie, i• n A. bz.onplrandi7;i;
is
^1
TVf
r ry.
enand,ra from t1he Old, Worl1d1 Tropics, h1 as involI ute
subsp. bonplandii^ which sometimes has the geni-
vernation. With involute vernation the developing
culum appearing remote for a few centimeters, but
bud) has both margins of the blade rolled
leaf
(in
appear be from other
does not otherwise to different
inward toward the midrib whereas super-
(Fig. &
1),
Cabrera
taxon Schultes
plants of the (see
common
volute vernation, the type of vernation
14083), Venation relatively uniform considering
is
Anthurium, has one margin inwardly
rolled to
for
major
the wide range of blade shapes. Usually the
the midrib and the other rolled around the coiled
Dom
pprroommiinneennttllyy oonn both ssuurrfiaacceess,, wwiitihn
vveeiinnss aarree rraaiisseedd
„
, _ , . . - , -I /T-
up inner blade marein, as well as the midrib (rie.
^ r u*i
^ t,he mi.d,ri.,b varyi• ng from sil-ightly convex *to anguliar
^\
2).
above and more prominently convex be-
typically
Although the presence of involute vernation
Is
Frequently, the midrib angular above, this
low.
if is
.is
Pachy-
consistent on adult plants, juvenile plants of
on
owing a continuation of a medial rib the
to
may
neurium species have supervolute vernation
u
-^ /^ adiaxi•ali surfrace oir tihe peti•olie, but. more commonliy
or a transi.ti. onal stage of development wh, ere only
the midrib at the very base on the adaxial
flat
is
„
has
a part of a leaf blade (usually the widest part) •
_
^ From , . . , .. mid.rib may ibecome
surface. this point the
cu
u
J
, . i>- rr comm.)\
involute vernation. Richard Sheffer /(pers.
more and more acute toward
progressively raised
from
reports observine a series of leaves a sinele
^ xu j-
/ t,he apex, t,he most acute porti• on tbe•mg i• n the dist*ali
r • ui
plant where the vernation of successive blad1es pro-
From com-
2/3 midrib
of the blade. this point the
gresses gradually from wholly supervolute blades
monly becomes diminished and usually even
Is
when juvenile, to partially involute blades to wholly
,•',,'.
,, .• t-u-
^ weakly sunk, en t,he very Ihis generalili y
,, -', _ ,^ at tip. is
.... . , .
mvolute Multiner-
blades in adult plants, in series
., j
, wh, en , ., ^i_ • r
true also the midrib on the adaxiali surface
*.
more
which has general slender blades, the
via, in
merely rounded or obtuse rather than acutely
is
of the blade frequently supervolute while the
tip is
raised.
remainder of the blade has typical involute ver-
On may
be convex
the lower surface, the midrib
nation. This failure of the apical portion to be
when due
or angular, but angular usually
it is it is
involute probably due to the difficulty in rolling
is
to an extention of the ribs onto the petiole. In this
up an increasingly narrower section of leaf tissue.
case, the ribbing on the abaxial surface of the
—
on geniculum
General features Although species in sect. petiole often present the as well,
is
Pachyneurium have oblanceolate A.
typically thick, e.g., in luteynii.
members Pachyneurium
to obovate leaf blades with short petioles, the group For typical of sect.