WOOD ANATOMY OF LIMNANTHACEAE AND TROPAEOLACEAE IN RELATION TO HABIT AND PHYLOGENY

10 Pages·1996·7 MB·English

by  Sherwin Carlquist

WOOD
ANATOMY LIMNANTHACEAE
OF
AND
TROPAEOLACEAE RELATION
IN
AND PHYTOGENY
TO HABIT
DONALD
JOHN
CHRISTOPHER
SHERWIN CARLQUIST
and
Santa Barbara Botanic Garden
1212 Canyon Road
Mission
CA
Santa Barbara, 93105, U.S.A.
INTRODUCTION
No on wood anatomy of either Limnanthaceae or Tropaeolaceae
data
& The
Chalk Gregory
1950; 1994).
have been presented to date (Metcalfe
divergent kinds
wood of these families interesting with respect to their
is
The two
members of both families are herbs. families are
of habits;
all
most herbaceous of the families recog-
grouped here because they are the
333-342. 1996
17(2):
.
among
nized the glucosinolate which may
families, be considered Capparales
Rodman
sensu by Dahlgren Rodman
lato, (1975), (1991a, 1991b) and
er
(1993, 1994). Formerly both Limnanthaceae and
al. Tropaeolaceae were
included
in Geraniales (e.g., Cronquist 1981; Thorne 1992). In some
re-
cent cladistic systems, Tropaeolaceae group
are a Akaniaceae and
sister to
Bretschneideraceae; Limnanthaceae
not away
are far in the clade of
among
Capparales and
groups
the Limnanthaceae
(s.l.), nearest to are
Batidaceae, Caricaceae, and Moringaceae (Rodman
et 1993, 1994).
al.
Tropaeolaceae and Limnanthaceae
are placed close to Capparaceae in the
cladogram who
of Conti
et al. (1996), include fewer of the glucosinolate
who
families in their survey, and therefore
offer less precision in the place-
ment
two
of these
families.
Rodman
et (1993) concede that marked evolutionary
al. shift in habit
must
be hypothesized
Tropaeolaceae
if are close to the tree families
Akaniaceae and
Bretschneideraceae. However, they do not consider
this
improbable and how
may
invite consideration of these changes have
oc-
curred. Similar considerations apply Limnanthaceae. The
to species of
known
Tropaeolum
studied, the well
majus, an annual herb with vining
T.
is
The
capabilities. base of the stem contains a cylinder of secondary xylem
mm
1-2
in thickness; the upper portion of the root contains xylem
a core
mm
1-3
in thickness; these have been used
in the present study. Limnanthes
woody
douglasn than
is less Tropaeolum; Limnanthes is an annual with a short
stem which numerous
basal
to thin
roots are attached; upwardly,
the basal
stem
branches into several prostrate stems. The patches of secondary xylem
in the stem of Limnanthes
are evidently
related to these prostrate stems.
These
distinctive habits, and the fact that secondary xylem in Limnanthaceae
and
Tropaeolaceae minimal
is in comparison with that of other capparalean
families provide reasons for study of wood anatomy of these two
families.
If
marked
differences in habit have occurred
phyletically in the divergence of
two from
these families their nearest neighbors, we will have new examples
how
wood
of nature of anatomy
To
reflects shift in habit. be only one
sure,
species of each family has been used The
in the present study. reason
for
this selection is that for each family, the species studied the woodiest
is
that could be obtained Further may
readily. studies are needed, but they
demonstrate more modes
herbaceous
of structure than do the species in the
present paper, judging from
the habits described Limnanthaceae by
for
Ornduff
and
(1971) Tropaeolaceae by
Sparre
et (1991).
al.
and
roots bearing secondary xylem from
plants oi Tropaeolum majus
anthes douglasn that were judged to be mature but not yet in de-
from
collected plants
5 in cultivation. In the case of the Tropaeolum,
plants were collected from a Santa Barbara garden where the species has
Umnanthes douglani were collected from Santa Bar-
Plants oi
naturalized.
bara Botanic Garden, where they have become naturalized, with the aid of
Mark The portions bearing secondary xylem were preserved in
Stubler.
Wood immer-
50% aqueous ethyl alcohol. oi Tropaeolum was softened by
5% diamine two hours. Material was infiltrated and
sion in ethylene for
on
embedded according the usual techniques, sectioned a
in paraffin to
microtome; sections mounted on slides were stained with a safranin-
rotary
green combination corresponding to Northen's modification of Foster's
fast
some
method (Johansen 1940). In addition, sec-
chloride
tannic acid-ferric
on micro-
unsoftened stems of majus were sectioned a sliding
tions of T.
between sputter coated, and examined with a scan-
tome, dried glass slides,
with
microscope (SEM). Macerations were prepared Jeffrey's
ning electron
and with
stained safranin.
fluid
lAWA
Committee on Nomenclature
Terminology follows that of the
which
The term "pseudoscalariform" refers to pitting in pits are
(1964).
from
but derived
scalariform pitting, are alter-
horizontally elongate, as in
markedly widened, and thus the ends of the pits do not
nate pits that are
lumen
were measured term of
in
correspond to angles of the vessels. Vessels
parenchyma
was estimated. The term "intervascular" axial refers to a situ-
among
parenchyma large
which are scattered
ation in occasional axial cells
parenchyma paren-
groupings of whereas paratracheal applies to
vessels,
chyma group.
surrounding a vessel or vessel
xylem limited
Umnanthes stem (Fig. 1-5). Secondary very in
doiiglasii
segments within the vascular cylinder
extent, and also localized in several
xylem
composed primary
of
intervening parts of the cylinder
(Fig. top),
1,
bottom). Vessels square or polygonal in outline, in large
only Fig.
(e.g, 1,
mean num-
parenchyma
groupings with few intervening axial cells (Fig.
1);
mm^
mean number per (no areas
ber of vessels per group, 18.1; of vessels
Mean
28.2
xylem 690. vessel diameter,
secondary included),
adjacent to
pm. Mean element length, 71.6 pm. Perforation plates all simple,
vessel
diameter Vessels
and appreciably narrower than the vessel (Fig. 4).
circular
irregular in outline, either as seen in tangential (Fig. 3) or radial (Fig. 4)
elongate,
Lateral wall pitting of vessels consisting of pits laterally
sections.
about
pseudoscalariform Lateral wall pits (pit cavity)
(Fig.
alternate to 5).
pm measured Imperforate tracheary elements ab-
vertically (Fig.
as 5).
5
parenchyma subdivided into strands
Axial sparse, intervascular (Fig. 2),
sent.
primary Rays uniseriate or
two not subdivided, with thin walls only.
or or
mean
Mean 238 pm; height of
height of biseriate rays,
biseriate (Fig.
3).

Wood
uniseriate rays, 91 1-im. Ray cells with thin primary walls. nonstoried
(Fig. no starch or crystals observed.
3),
wood
Tropaeolum majus stem 8-15). Axial portions of consisting
(Fig.
6,
Wide
dimorphic diameter
largely of vessels in (Fig. vessels solitary or in
6).
number mean
(mean of per group nonray diam-
pairs vessels in areas,
1.8),
81 pm. Narrow vessels comprising the bulk of the remainder of the
eter,
mean
secondary xylem and therefore in indefinitely large groups; diameter
Mean
of the narrower vessels, 29 pm. length vessel elements (wide and
Mean
narrow vessel elements combined), 116 pm. wall thickness of vessels
pm pm
varying from 1.8 for narrower vessels to 2.5 for wider vessels. Per-
foration plates mostly simple, but occasional scalariform or scalariformlike
plates present (Fig. 12-15): some plates with numerous forked or intercon-
some with few some, on narrow
nected bars (Fig. 12), bars (Fig. 13), ves-
with wide some with condition intermediate between
bars (Fig. 14), a
sels,
scalariform and multiperforate (Fig. 15). Lateral wall pitting of vessels al-
pm
about measured
ternate, pits circular to oval (Fig. 9, left) or elliptical, 5
formed
vertically. Libriform fibers present, especially in earlier portions of
xylem by
secondary xylem, supplanted in later portions of axial secondary
narrow Libriform with simple and often containing starch
vessels. fibers pits,
Mean 462 pm; mean diam-
grains (Fig. right). length of libriform fibers,
9,
A
24 pm; mean wall thickness, 2.2 pm. few vasicentric tracheids and
eter,
between and
few intermediate pitting libriform vasicentric
a cells in fibers
tracheids present. Axial parenchyma with thin secondary walls, in strands
more
of two adjacent to the larger vessels. Rays multiseriate only,
cells,
pm
Mean
mean width
than 1,000 in height (Fig. right). of multiseriate
8,
12 Ray with thin primary walls, bearing prominent pit
rays, cells. cells
on separated from each other by horizontal bands of
fields radial walls,
primary wall material Ray predominantly upright; square
(Fig. 10). cells
Wood
and procumbent cells in central portions of rays (Fig. 10). nonstoried
abundant
(Fig. Starch in ray cells (Fig. 10), starch grains spherical in
8).
shape
(Fig. 11).
wood
mostly
Tropaeolum majus, root (Fig. Axial portions of consisting
7).
mean num-
of vessels dimorphic in diameter. Larger vessels mostly solitary,
ber of vessels per group, 1.4. Narrower vessels in groups of indefinite ex-
Mean
Mean number diam-
tent. of larger vessels (ray areas excluded), 44.8.
eter of larger vessels, 96 pm; mean diameter of narrower vessels, 27 pm.
Mean
Mean pm.
wall thickness of vessels varying from 1.8 to 3.5 length of
pm.
vessel elements (wide and narrow vessel elements together), 99 Perfo-
ration plates and lateral wall pitting as in stems. Libriform fibers very few;
parenchyma two
few vasicentric tracheids present. Axial in strands of
a
Rays
with secondary walls, adjacent to the larger vessels. multiseriate
cells,
Mean 1460 pm; mean
and height of multiseriate
uniseriate (Fig. rays,
7).

height of Liniseriate rays, 312 \im. Ray cells mostly upright, a
fe^
and procumbent
cells present in central portions of multiseriate
ra^
width Ray
of multiseriate rays, 5.1 cells. cells thin-walled, nonl
Wood
vague
nonstoried, btit storying visible in tangential sectior
ondary phloem. abundant
Starch grains in ray
cells.
Limnanthes and Tropaeolum differ in a number of salient ways with
re-
wood
spect to anatomy. Limnanthes douglasii has narrow vessels angular in
nondimorphic
transection, in diameter, with simple perforation plates ex-
and with mostly
clusively pseudoscalariform lateral wall pitting; imperfo-
rate tracheary elements are entirely absent; axial parenchyma sparse and
is
with
thin nonlignified composed
walls; rays are uniseriate or biseriate, of
upright cells. Tropaeolum majus has markedly dimorphic vessels; the larger
are circular in transectional outline, the smaller circular to angular in out-
line; lateral wall pitting mostly circular to elliptical; perforation plates
is
simple, but with an number
are appreciable of perforation plates that rep-
resent alterations of a scalariform pattern; libriform fibers with simple pits
are present (somewhat abundant than the narrow but few
less vessels), a
vasicentric tracheids and cells intermediate between libriform fibers and
parenchyma
vasicentric tracheids are present; axial has thin lignified walls,
is in strands of two cells, and is distributed adjacent to the larger vessels. In
wide and
T. majus, rays are exclusively multiseriate in stems in roots, rays
mostly and
are multiseriate less wide; ray cells are thin walled, with
filled
starch, and are mostly upright, but with procumbent and square
cells in
central ray portions.
The
may
lack of imperforate tracheary elements in Limnanthes be corre-
lated with lack of upright stems, because libriform would be ex-
fibers
pected where addition of mechanical strength of The
selective value.
is
occurrence of secondary xylem in small restricted patches related the
to
is
short duration of this annual, and the short stem. Secondary xylem appar-
ently connects the branches with the basal stem, and the remainder of the
basal stem contains primary xylem only. Thus, habit seems correspond
to
The
to those distinctive features. shortness of vessel elements in Limnanthes
xeromorphy;
is likely related to short vessel elements are found in plants of
habitats that dry as a season progresses (Carlquist 1966).
wood
Tropaeolum dimorphism
distinctive in the of vessel diameter,
is its
in the sparsity of libriform fibers (supplanted to a large extent by narrow
common
and
vessels), in the very wide, tall rays. These are features in woods
of vines and lianas (Carlquist 1985). The relative shortness of vessel ele-
ments
in L. majus is likely related to the drying of soil as the plant reaches
wood
Other between the oi Limnanthes and that o^Tropaeolum
differences
wood
seem related to phylogenetic relationships. For example, the of
Akaniaceae and Bretschneideraceae (Rod-
Tropaeolaceae, placed close to
man number wood
1993, 1994), shares with that pair of families a of
et
al.
features (wood of those two families monographed by Carlquist, submit-
number
simple but with an appreciable of modified
perforation plates
ted):
parenchyma
scalariform perforation plates; libriform fibers present; axial
Akaniaceae
sparse, distributed adjacent to the larger vessels (vasicentric in
and Bretschneideraceae); rays wide and uniseriate rays few or absent
tall,
(wide rays also a characteristic of vines and lianas, but absence of uniseriate
On wood
the other hand, some of the features oi Limnanthes can be found
genera of Capparales from which not far removed according to the
in it is
Rodman
schemes of et (1993, 1994). For example, in Capparaceae, rays
al.
&
Chalk
multiseriate (Metcalfe 1950).
are uniseriate or biseriate, rarely
The marked between annual Limnanthes and genera
habit the
difference in
of Capparaceae, which are trees or shrubs, means that modifications related
and
be of overriding importance, similarities related
to habit are likely to
on wood anatomy
be Further studies
phyletic relationship are likely to few.
to
may
of the glucosinolate families, which tentatively be considered a redefined
Capparales, are planned so as to show the relative degrees of influence that
habit and phylogenetic relationship have on similarities and differences
among component
the families of that order.
wood
histology of v
1
Columbia
of flowering plants.
classification
>f
demon-
on angiosperms be used
of the to to
lAWA
wood anatomy
of dicotyledons.
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New
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R.A. Piucii, K. Karol, E. Conti, K.J.K, and J.D. Palmer. 1993. Nude-
,
sequences of the rlxL gene indicate monophyiy of mustard
:»ticie oil
;oun Bot. Card. 80:585-699.
K.G. Karol, R.A. Price, E. Conti, and Sytsma.
K.J.
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