THE GENUS RYTIDOSPERMA (POACEAE) IN THE UNITED STATES OF AMERICA

2010·8.1 MB·English

by  Stephen J Darbyshire

THE GENUS RYTIDOSPERMA THE UNITED OF AMERICA
(POACEAE) STATES
IN
Stephen Henry Connor
Darbyshire
J. E.
nly in California, Oregon and Hawaih (Whitney
e
&
1939; Darbyshire Connor Dean
2003;
6
The genus Rytidosperma 3m
is distinguis Danthonia sensu stricto primarily by the presence of
transverse rows of hairs on the back of th< a (Figs. 1-3). These hairs may be in discrete tufts or form
more One
or continuous row
less lines. occurs towards the base just above the callus and the other towards
the apex just below the awn Rows, may
sinus. especially the upper, be reduced
to tufts only the margins.
at
Other hairs may or may not be back lemma
scattered across the of the between the rows. In some species the
lemma back indumentum may
be lacking altogether, while in other species the lemma back more
or
is less
evenly covered by hairs with no distinct trace of the two rows of Ensheathed
tufts. spikelets, cleistogenes,
were reported by Chase many
(1918) in the leaf axils of species of Danthonia
(including
“D. semiannularisl,
&
but these are absent from Rytidosperma (Vickery 1956; Connor Edgar
1979). Florets of the exserted
inflo-
may &
rescences be chasmogamous
either or cleistogamous (Edgar Connor
2000).
Descriptions and measurements &
given here follow the conventions of Connor Edgar and
(1979)
are based primarily on plants of North American and Hawaiian
chromosome
origin. Meiotic counts
of R.
racemosum and
R. richardsonii were determined on grown
plants from
seed obtained from
collections
origi-
nating in California. These counts
are indicated in square
brackets
after the original collection
citation.
Voucher specimens chromosome
for counts of R. racemosum and DAO
R. richardsonii are deposited with
at
CHR
associated material DAO, and UC. Counts New
at
of plants of Zealand provenance
are presented
for
AK
R. caespitosum; vouchers are deposited and CHR.
lemmas
at Illustrations of are prepared from North
American New
drawings) and
(line Zealand
(color paintings)
material.
This study
primarily focused on
is species that have become
naturalized in the United however,
States;
icluded since undetected
have
occurred.
e; ell
provide examples known
of poorly when
species, or they provide information on
introduction
sit
TAXONOMIC
TREATMENT
Rytidosperma
Steud., Syn. Glum.
PI. 1:425. 1854.
Type: Rytidosperma
lechleri Steud.
New
l^oiodanthoma
Zotov, Zealand
J. Bot. 1:104. 1963. Type: Notodanthonia unarede (Raoul)
Zotov.
Austrvdanthorua H.E Under, Telopea
7:269. 1997. Type AustrodaKthoma
caespnosa (Gaudich.) H.P Under.
Plants
perennial, densely
or loosely
cespitose, sometii Culms
(1.5-)30-90(-140)
i.
cm,
erect or nodding. Leaves
usually mostly
basal;
s
apices usually with
tufts of hairs, sometimes extending
across'.he
collar; ligules a rto orhahsrblaies
persistent or
disarticulating,
involute or
flat, convolute, glabrous
or variously pubescent. Inflorescences
terminal, racemes
or panicles. Spikelets somewhat
laterally compressed, with 3-10
florets- florets bisexual
chasmogamous
or cleistogamous,
terminal
florets reduced; disarticulalion
above the glumes and between
mm
glumes
the (2-)8-20
florets;
long, subequal
or
equal, usually exceeding
the florets (excluding awns),
membranous, 3-13
sti fly
veins, usually with
scarious margins; calluses sharp somewhat
or blunt with
latera tufts of stiff hairs, disarticulation lemmas
oblique; main lemma
(the body)
ovate to lanceolate with 2
complete orincomplete
transverse rows
of tufts of sometimes
stiff hairs, reduced
marginal
to 5-9(-ll)
tufts
veins, apices bilobed, the lobes
usually
at least as long as the body,
acute or acuminate with a long awn-
hke awn
arista; a central between
the lobes and
longer than them,
usually proximally
twisted below
into a
column,
usually
geniculate or
reflexed; lodicules
2, fleshy, usually with apical hairs or glabrous; anthers
vary
greatly in size depending on
whether
they from
are cleistogamic chasmogamic
or
<
flowers
mm (usually
and > mm, mm
1.2
1.8
respectively). Caryopses
1.2-3
long, obovate
to elliptic, golden dark brown,
to
ree, hila punctiform somewhat
to
Cleistogenes
elliptic. not formed. x2 = (Murray Name
12 2005)
et
al.
from
the Greek &
rhytidos, “wrinkles,” and sperma,
“seed” Connor
(vide Edgar
1979).
Darbyshire et al., The genus Rytidosperma in the U.S.A.
665
KEY TO THE
OF
SPECIES RYTIDOSPERMA NATURALIZED UNITED
IN STATES OF AMERICA
E
Upper lemma
hairs in isolated tufts or at margins only and not forming a
.
2. Callus of second lemma 0.5-1. long, hairs usually overlapping the lower
1 its ro\
narrowed
gradually to a fine awn-like arista
2. Callus of second lemma 1-1.5 r )ng, its hairs rarely or just reaching lower row of le
mm
lemma
5-10
lobes long, abruptly narrowed to a fine avyn-like
arista
Lemma
two
hairs in continuous transverse rows of tufts, with or without hairs between tt
.
mm
mm
awn
3. Central 10-20 long, column 4-5 long
mm mm
awn
3. Central usually less than 10 long, column 0.5-3 long.
Timas 1.8-2.4mmlong;av
n 2.5-3
I
not reaching upper
jally
rc
mm
3-4 awn
Timas
long; long, sparingly twisted;
1 Ic
?riapping upper row
&
Rytidosperma New
biannulare Connor
(Zotov) Edgar, Zealand Bot. 17:324. 1979. (Fig. 1C, 3B).
Noto-
J.
Culms
Plants caespitose. 30-85 cm, erect, smooth and glabrous, glabrous below inflorescence, branching
intravaginal. Leaves mostly basal, exceeded by the culms, flag leaf blades usually reaching or exceeding the
mm
inflorescences; sheaths mostly glabrous, often purplish distally, apical tufts of hairs to 5 or sometimes
mm
mm; 30-40 cm
absent; ligules 0.3-0.5(-l) blades long, to 5 wide, usually involute, margins, apices.
cm
Inflorescences paniculate, 10-20 long, narrow and compact; rachis scabrous; pedicels shorter than
mm mm
6-7 glumes
spikelets, scabrous. Spikelets (7-)10-15 long, with florets; 7.5-ll(-13.2) long, surpass-
ing florets, subequal, lanceolate, acute, glabrous, light green to stramineous usually purple at margins and
mm
apex; lower glumes 5-7(-9) veins; upper glumes 5 veins; rachilla segments 0.3-0.5 long; calluses
mm mm mm
lemma lemmas
0.5-0.7 long, hairs to about and reaching the lower hairs; 1.8-2.4(-2.8) long,
1
hairs of lower row usually not or only just reaching the upper row, lower row sometimes ill-defined, hairs
awn lemma
of upper rows reaching or surpassing the column apex but not the apex of the lobes, with short
mm
awn
scattered hairs (rarely glabrous) between the rows; lobes 3.5-5(-8.5) long, acuminate; 6-10(-12.5)
mm mm mm
lemma
long, twisted column 2.5-3 long; paleas 2.5-4.6 long, exceeding the sinuses, obovate,
emarginate, sparsely hairy between the veins, margins usually with long hairs, veins ciliate; anthers 0.8-1
.6
mm mm mm mm
mm;
long. Caryopses 2-1.9 x 0. 6-0.8 embryos 0.5-0.8 long; hila 0.3-0.6 long. 2n =
1.
New
Zealand (Murray 2005).
48; plants et
al.
A
from southwestern Oregon (Peck 23954) and another from Maui (Hobdy 2389) provide
single collection
the only evidence that this species may have naturalized in the United States, although cultivated specimens
grown
from Santa Cruz Co., California, have also been seen (Fig. 4A). The species has been experimentally
in North America under the name Danthonia semiamularis (Labill.) R. Br., possibly as early as 1905 (Wein-
name
traub 1953). However, as pointed out by Vickery (1956), D. semiannularis is a that “has been used for
almost any but and more than one species was probably imported to North America under
the true species”
New unknown
Zealand and
this name. Since tetraploid R. biannulare is regarded as native to in Australia,
this species may have been more recently introduced than the early 20th Century importation of Australian
species.
Whitney (1939) and Wagner (1999), respectively, reported R. semiannulare as introduced to
et et al.
al.
the state of Hawai'i (on Molokai) in 1903 and first collected (on Maui) in 1937. The 1937 specimen (Hosaka
from
1767) however, referred to R. caespitosum. Label data on a relatively recent collection of R. biannulare
is,
West Maui (Hobdy 2389) suggest that this species has naturalized there.
May
Specimens examined: CALIFORNIA. Santa Cruz Co.: Ives plots near Aptos, Corralitos area, Icultivated], 20 1940, P.B. Dicfeey 920.
Journal of the Botanical Research Institute of Texas
4(2)
Darbyshire et The genus Rytidosperma the
al., in U.S.A. 667
D920 (AHUC, US). HAWAI‘1. Maui: West Maui, Hanaulaiki, elev. 3500 ft, May 1985, R. Hobdy 2389 (BISH). OREGON. Curry Co.: 5
mi S of Gold Beach, shady bank, 23 Jul 1945, M.E. Peck 23954 (WILLU).
&
Rytidosperma New
caespitosum Connor
(Gaudich.) Edgar, Zealand Bot. 17:325. 1979. (Fig. 2B, 2C,
J.
Plants densely to loosely caespitose, sometimes shortly rhizomatous. Culms 43-80 cm, smooth and
erect,
glabrous, glabrous or sparsely scabrous immediately below the inflorescence, branching intravaginal (or rarely
extravaginal). Leaves mostly basal, usually exceeded by culms, flag leaves sometimes reaching inflorescence;
mm mm
sheaths 1-4
glabrous or pilose, apical tufts of hairs long, sometimes scanty; ligules (0.3-)0.5-1.2
mm
cm
long; blades 6-25 long, 1.5-3 wide, involute or more or less glabrous or variously pubescent.
flat,
cm
Inflorescence paniculate, 5-1 1 long, linear to ovate, more or less compact; rachis scabrous to somewhat
mm
pubescent; pedicels shorter than spikelets, scabrous to somewhat pubescent. Spikelets 10-20 long,
mm
4-9
glumes
9-18(-20) surpassing subequal unequal, acuminate,
florets; long, florets, to lanceolate,
glabrous or sometimes with scattered long hairs, light green to stramineous often purple at margins and apex;
mm
lower glumes (l-)3-5(-7) veins; upper glumes (3-)5-7(-9) veins; rachilla segments 1-0.4 long;
0.
mm
awn column lemma
about 3.5 long and reaching or surpassing the palea apex but not apex of or lobes,
mm mm
awn
10-20
glabrous between the rows; lobes (6-)7-10 long, acuminate or aristate; long, tightly
mm mm
4-6 lemma
twisted column long; paleas 5-5.5 long, surpassing sinus, lanceolate to obovate,
2.
mm
emarginate, glabrous between the veins, margins with a few long hairs, veins ciliate; anthers 0.5-2. 6
mm mm mm
=
long. Caryopses 1.7-2. 3 x 0.8-1. embryos 0.7-1 long; hila 0.25-0.7 long. 2n 24, 48, 72;
1;
&
New
Australian plants (Abele 1959; Brock Brown 1961; Waters et al. 2010). 2n = 24; Zealand plants (B.G.
& AK CHR
Murray de Lange, hie comm.; 25913C, 549710).
J.P.
A
Grasslands, pastures, rangelands and disturbed areas up to 200 m. highly variable and widespread
species with co-occurring polyploid races indigenous to southern Australia (Vickery 1956; Abele 1959;
&
Brock Brown 1961; Waters et 2010). Rytidosperma caespitosum has naturalized at a few scattered loca-
al.
WA,
tions in California (Berkeley, Pescadero and San Diego regions), and has been cultivated at Pullman,
and Two form Hawai'i by Hosaka in the 1930s are referred
several sites in California (Fig. 4B). collections
may
to this species, but the lack of recent collections suggests that it not have persisted. It has also been
among
naturalized in New Zealand since at least 1892 (Zotov 1963). It is listed, with some uncertainty, the
Ryves
Kingdom through discarded wool-waste (Lousley 1961; 1988).
species introduced to the United

iintheU.S.A.
670
Journal of the Botanical Research Institute of Texas
4(2)
Plants densely somewhat Culms
to loosely caespitose to spreading, shortly rhizomatous. (22-)30-90
cm, smooth and
erect, usually glabrous, usually scabrous-pubescent immediately below
the inflorescence,
branching
extravaginal, cataphylls scaly. Leaves mostly basal and greatly exceeded by the culms,
flag leaf
blades usually not reaching the inflorescence; sheaths densely hairy or glabrous, apical tufts of hairs 1-3.5
mm
mm
mm
cm
long; ligules (0.1)0.3-1 long; blades 30 long and
to to 5 wide, folded, or involute,
flat,
glabrous, scabrous or pubescent. Inflorescences racemose cm
or paniculate, (3-)4-10 long, ovate to lin-
compact; rachis
ear, scabrous to finely pubescent; pedicels than
shorter the spikelets, glabrous, scabrous
mm
mm
or finely pubescent. Spikelets 9-15(-18) glumes
long, 5-7(-10)
florets; (7,3-)8-13(-17.5) long,
surpassing subequal,
florets, lanceolate, glabrous, scabrous, or sometimes with scattered green
hairs, light
stramineous
to often purple at margins and apex; lower glumes 5-9(-ll) veins; upper glumes 5-7(-9)
mm
mm mm
segments
veins; rachilla 0.2-0.5
long; calluses 0.5-1.3 long, hairs about 1.5 long and usually
mm
reaching the lower lemma lemmas
hairs; (2-)2.5-4.2 row
long, 9(-ll) veins, lower of hairs continu-
ous or with weak
(rarely absent)
central tufts, hairs of the marginal usually reaching upper row
tufts the of
upper row
hairs, of hairs composed of 2 marginal tufts, sometimes with 2 additional scanty between,
tufts
mm
hairs reaching or slightly exceeding the base of the awn, otherwise glabrous; lobes 5-ll(-13)
long,
mm
awn mm
acuminate,
anstate; (7-)9-17.5 column
long, tightly twisted 1.5-4 long, somewhat reflexed
mm
base and
at revealing palea apex or not; paleas 3-6 long, exceeding the lemma sinuses, emarginate,
intercostal region glabrous
or scabrous, margins glabrous or with sparse long hairs, veins anthers
ciliate;
mm
mm
0.4-2.7 Caryopses mm; mm
long. 1.8-2.5(-3) x K-1.6) embryos
0.8-1. 0.7-K-1.5) long; hila
mm
&
(0.3-)0.4-0.5(-0.7) =
long. 2n 24; Australian plants (Abele 1959; Brock Brown and
1961) Californian
plants (Myers 1947
Danthonia
[as
pilosa]).
Commonly
growing on
dry, nutrient-poor soils. Habitats include pastures, rangelands and disturbed
m
m
areas at elevations up to about 800 in California, and about 1675-2840 common
in Hawai'i.
is a
It
weed
in coastal regions of California and southwestern Oregon
(Fig. 4C). At best, only of moderate forage
value in the United where
States usually considered troublesome
it is a pest competing with more desirable
&
species (Murphy
Love
1950; Stone
et 1992).
al.
An
Australian species, R. penicillata has been incorrectly known many
in the United
States for years
under name
the Danthonia
Hitchcock Sampson
pilosa R. Br. (e.g., 1951; et 1951; Weintraub Various
al. 1953).
common
names
have been
used, including hairy danthonia,
hairy oatgrass, Australian oatgrass and poverty
grass. Although considered poor
it is a quality forage grass, was introduced and
it tested in the continental
states in 1911 and again in 1921 (Weintraub By
1953). the 1940s had become
troublesome weed
it a at scat-
tered mainly &
localities in coastal areas from southwestern Oregon
to central California (Murphy Love
Sampson
1950;
et al. 1951). Introduced to the Hawaiian
Islands about 1910 (Whitney BISH
1939;
et al.
New
and
624327) Zealand
to as early as 1840 (Zotov now
1963), well
it is established in these regions. In
the United Kingdom, has been
reported as introduced with
it wool-waste
(Lousley 1961; Ryves but
1988),
has not become
fully naturalized
(Stace 1997).