Anatomy of Nodal Regions and Leaves in Hedysarum and Related Genera (Leguminosae)

15 Pages·1999·1.5 MB·English

by  Byoung-Hee Choi

植物研究雑誌
J. Jpn. Bot.
74: 236-250 (1999)
Anatomy of Nodal Regions and Leaves in Hedysarum
and Related Genera (Leguminosae)
b，*
Byoung-Hee CHO(，T omoyuki NEMOTO~' and Hiroyoshi OHASHI
aDepartrnent of Biology，In ha University，In cheon，40 2-751 KOREA;
bBiological Institute，Gr aduate School of Science，To hoku University，Se ndai，98 08578JAPAN
・
*Current address: Departrnent of Basic Sciences，Fa culty of Science and Engineering，Is hinornaki Senshu University，
Ishinornaki，9 86-8580 JAPAN
(Received on February 3，1 999)
Vascular system from the stem to petiole and anatomical and epidermal features
of the leaf were examined in Corethrodendron，He dysarum，St racheya and Taverniera.
Two types of the vascular system were observed at the node: trilacunar type and
multilacunar type. The trilacunar type was found in subgenera Gamotion and
Hedysarum of genus Hedysarum and genus Stracheya. It is the commonest type
among the taxa examined. On the other hand，th e multilacunar type was restricted
in subgenus Heteroloma of genus Hedysarum and genus Taverniera. The vascular
systems at the node of stem and at the base of petiole in the taxa examined are not
associated with number of leaflets and length of internodes which have been regarded
as important diagnostic characters in classification for these four genera. The peti-
oles have bundles fused altogether at least once at the base in all the species exam-
ined except Hedysarun spinosissimum of subgen. Hedysarum which has open (free)
bundle system. Although the species of subgen. Hedysarum have unique stipules，n o
specific vascular systems were observed. The bundle sheath extention of lateral vein
of leaflets was observed only in sect. Gamotion of subgen. Gamotion of Hedysarum.
Also，th is section differs from other sections of the subgenus by lacking ad istinctly
developed cuticular membrane. Stracheya is similar to subgen. Gamotion of
Hedysarum in anatomical characters of the node and the leaf. Subgen. Heteroloma
of Hedysarum is closer to genera Corethrodendron and Taverniera than other sub-
genera of Hedysarum in the characteristics of nodal anatomy，le af traces and leaf
epidermis.
Key words: leaf epidermis，p etiole，L eguminosae，tr ibe Hedysarae，v ascular system
Introduction 1971，C hoi 1988，C hoi and Ohashi 1996)，
Hedysarum and its related genera belong- but has been distinguished from these gen-
ing to the tribe Hedysareae of subfamily era by number of leaf1ets and shape of fruits.
Papilionoideae in Leguminosae (Hutchinson However，d elimitation of these four genera
1964，Po lhill 1981 a) are distributed in tem- is still controversial (Polhill 1981 b，T hulin
perate to boreal regions of Northern Hemi- 1985，C hoi 1988，C hoi and Ohashi 1996). In
sphere. Hedysarum is closely related to order to clarify intergeneric relationships
Corethrodendron，St racheya and Taverniera among Hedysarum，C orethrodendron，
in gross and pollen morphologies (Ohashi Stracheya and Taverniera，a nd infrageneric
-236-
August 1999 Journal of Japanese Botany Vo .l74 No. 4 237
relationships in Hedysarum，w e examined node and first leaflet pair. Only one nodal
vascular systems at the nodal regions and region with ap etiolar base was used from
petioles of leaves and anatomical and epi- one herbarium specimen for each species to
dermal features of leaves in these genera. examine the vascular system from the upper
Although taxonomic significance of such internode to the petiolar base，wh ile leaves
studies in Leguminosae was already empha- from one or several specimens were used for
sized by Watari (1934)，o nly af ew anatomi- each species to examine the vascular pattern
cal studies on branching patterns of leaf of the petiole. The material was frozen in
traces at the base of petioles have been liquid nitrogen in af oil boat，a nd then sec-
made in tribe Hedysareae. Vogelsberger tioned at at hickness of 15-20μm using a
(1893) studied anatomical features of leaves freezing microtome in ac old box. The sec-
and stems on several species of Hedysareae. tions were adhered to slides by albumine
He found several types of stomata and lea個.f and washed in distilled water at 700C for
veins and tannin in stems. Northstrom about 20 min. The sections were stained
(1974) described anatomical features of the with 1% safranine，d ehydrated in an etha-
stem，I eaflet and petiole together with nol series，cl eared in xylol and mounted in
flower，l oment，s eed and root in No rth Canada balsam. The serial sections of each
American species of Hedysarum，bu t did not sample were examined and drawn by a
add taxonomic consideration. Leaf anatomy Zeiss-111 photomicroscopy.
of several species of Taverniera and For the observations of cross sections and
Hedysarum was made by Thulin (1985)，bu t epidermal surfaces of leaflets，le aflets were
no significant differences between the two collected from herbarium specimens and
genera were found. fixed by FA Aa t first. The cross sections of
Vascular systems from the stem to peti- them were obtained by hand using ar azor，
ole and anatomical features of the leaf epi- dehydrated by an ethanol series，tr ansferred
dermis are studied in this work，th erefore，in to isoamyl acetate，dr ied in ac ritical point
order to find useful characteristics to clarify dryer，m ounted on aluminum stubs with a
intergeneric relationships among Hedysarum silver paste，c oated with gold，a nd then ob-
and its related genera and the infrageneric served in aJ EOL JSM 840 scanning elec-
relationships in genus Hedysarum. tron microscopy (SEM). Some specimens
were frozen in liquid nitrogen and observed
島faterialsand Methods with aS M-CRU 40 crio-system using the
Most of the materials examined in this SEM.
study were obtained from herbarium speci-
mens listed in Appendix 1. A few materials Results
were obtained from fresh plants cultivated in 1. Vascular system at the node
the green house of Biological Institute， Vascular systems at the node were exam
目
Tohoku University. ined in seven species of He dysarum，w hich
The materials from herbarium specimens represent three subgenera and four sections，
were softened in boiling water for about 10 Stracheya tibeticαand Taverniera
min. For the study of vascular systems of nummularia (Appendix 1.1). Leaf traces
the nodal regions，s ections were taken from were bent toward the base of leaf petiole
the upper internode of stem through the from the vascular cylinder in the stem. In
node to the petiolar base，a nd for the vascu- the transverse sections of the nodal regions
lar system of petiole，f rom the middle part trilacunar or multilacunar nodes were ob-
of the petiole，t hat is，m id length between served (Table 1).
238 植物研究雑誌第74巻第4号 平成11年8月
Table 1. Leaf and nodal anatomical characters investigated in the present study of Hedysarum and related
genera
Number of Leaf gap Stipule Lateral vein Cuticle Vascular type
leaflet of leaflet on leaflet of petiole*l
Corethrodendron more than 5 NI sheathing obscure developed F
Hedysarum
Subgen. Gamotion
Sect. Crinifera more than 5 NI sheathing obscure distinctly C&D
developed
*2
Sect. Gamotion more than 5 3 sheathing consplcuoUS developed C&D
Sect. Membranacea more than 5 3 sheathing obscure developed F
Sect. Multicaulia more than 5 3 sheathing obscure distinctly C
developed
Sect. Subacaulia (1-3) or 3 sheathing obscure distinctly B&C
more than 5 developed
Subgen. Hedysarum more than 5 3 free，ad nate obscure developed A&E
with petiole
Subgen. Heteroloma more than 5 5 sheathing obscure developed F
Stracheya more than 5 3 sheathing obscure developed E
Taverniera 1-3 3+1 sheathing obscure developed E
*1 *2
NI，no t investigated; "s ee text f~o r the explanation; ，-with bundle-sheath extention.
1) Tri1acunar node: Three leaf traces are ole. This form was observed only in the
coming out from the vascular cylinder of the species of subgenus Heteroloma of genus
stem leaving three gaps. This type of the Hedysarum (Fig. 4A). The other has four
node，t rilacunar node，is most common in leaf traces (Fig. 7A )，on e of which is signifi-
the species examined，a nd observed in sub- cantly smaller in size than others. Wec all
genera Gamotion and Hedysarum of genus it an‘additional trace' in the present study
Hedysαrum (Figs. lA，2 A，3 A，5 ) and ‘(at' in Fig. 7A) . This additional trace fused
Stracheya tibetica (Fig. 6). with one of the lateral bundles before enter-
2) Multilacunar node: More than three ing into the petiole (Fig. 7B). This form was
leaf traces are coming out from the vascu- observed only in Taνerniera nummulariα
lar cylinder leaving each gap，a nd this is (Fig. 7A ，B) .
multi1acunar type. Two forms were found
with respect to the number of leaf traces in 2. Vascular system from the node to petiolar
this type. One has five leaf traces，e ach of base
which is almost equal in size and not fused General feαtures: The vascular system
with each other before entering into the peti- between the node and the base of the peti-
August 1999 Journal of Japanese Botany Vo .l74 No. 4 239
Fig. 1. Diagrams of vascular bundles from nodal region to petiole in Hedysarum gmelini. A，
B. Nodal region from proximal to distal parts. C-G. Petiolar base from proximal to distal
parts. H. Middle part of petiole. Hatched and dotted areas show xylem and sclerenchyma，
respectively. br，br anch trace; ss，sh eathing stipule; st，st ipular bundle.
ole was examined in six species (Appendix base of petiole.
1.1). At the internode of the stem，v ascular 1) Hedysarum gmelini (subgen. Gamotion
bundles form ac ontinuous ring in all species sect. Multicaulia: Figs. lA-H): Three leaf
examined. At the node，l eaf traces are traces branched off from the vascular cylin-
branched off from the vascular cy linder of der of the stem change their forms from
the stem leaving each gap (Figs. lA，2 A， those fused altogether to those segmented
3A，4 A，5 ，6 ，7 A) . Two branch traces are into small bundles or those connected with
branched off from the vascular cylinder of an arc at the petiolar base even within the
the stem at the both sides of the median gap. same petiole (Fig. 1C- G).
In the species having the trilacunar type of 2) Hedysarum monophyllum (subgen.
node，t wo lateral gaps are closed to form an Gamotion sect. Subacaulia: Fig. 2A-E):
arc with an opening behind two branch Among three leaf traces branched off，t wo
traces ('br' in Figs. lB，2 B，3B ). The stipu- lateral leaf traces are smaller in size than the
lar bundle is branched off from each of two median trace (Fig. 2B). The three leaf traces
lateral traces，a nd extends to the sheathing separately enter into the petiolar base (Fig.
stipules surrounding the stem ('st' in Figs. 2C) and then completely fuse into ab undle
lB，2 B，3 C，7 B). The vascular bundles of of semilunar shape (Fig. 2D).
the stem are fused to form ar ing again 3) Hedysarum spinosissimum (subgen.
above the node. On the other hand，th e leaf Hedysarum: Fig. 3A占):In the whole peti-
traces run separately and then fuse or con ole，t hree leaf traces are completely sepa-
田
nect with each other before entering into the rated，th at is，f orming an open system. In the
240 植物研究雑誌第74巻第4号 平成11年8月
'..st
Figs. 2-3. Diagrams of vascular bundles from nodal region to petiole in Hedysarum
monophyllum (2A-2E) and H. spinosissimum (3A-3E). A，B. NodaI region from proxi-
mal to diataI parts. C，D . Petiolar base from proximal to distal parts. E. Middle part of
petiole. Hatched and dotted areas show xylem and scIerenchyma，r espectively. br，
branch trace; s，st ipule adnate with petiolar base; ss，s heathing part of stipule; st，st ipular
bundle.
petiolar base，t he median bundle is seg- (Fig. 3C).
mented into three parts first (Fig. 3C) and All species comprising subgen.
then they are fused into one bundle again Hedysarum are annual herbs except H.
later (Fig. 3D). Two lateral bundles are seg- coronarium of ap erennial herb. In this spe-
mented and fused again like the median cies，h owever，th e pattern of vasculature at
bundle (without illustration). Although this the petiolar base was not similar to that of
species has unique stipules basally adnate H. spinosissimum，b ut to that of H. gmelini
with the petiole (Fig. 3C，D )，s tipular (subgenus Gamotion; Fig. 1) in having al-
bundles (st) are branched off from lateral most fused bundles.
traces like other species with sheathing 4) Hedysarum fruticosum subsp.
stipules and segmented into three traces mongolicum (subgen. Heteroloma: Fig. 4A，
August 1999 Journal of Japanese Botany Vo .174 No. 4 241
Figs.4-7. Diagrarns of vascular bundles of nodal region and petiole in Hedysarum，S tracheya and
Taverniera. 4. H. fruticosum subsp. mongolicum: 4A，N odal region; 4B，Pe tiolar base. 5. Nodal
region of H. vicioides var. japonicum. 6. Nodal region of S. tibetica. 7. T. nummularia: 7A-
7B，N odal region from proximal to distal parts; 7C-7E，Pe tiolar base frorn proximal to distal
parts; 7F，M iddle part of petiole. Hatched and dotted areas show xylem and sclerenchyrna，re -
spectively. br，b ranch trace; ss，s heathing stipule; st，s tipular bundle.
B): Five leaf traces come out from the vas- bundles (Fig. 7C). The lateral bundles are
cular cylinder of the stem (Fig. 4A). These segmented and then connate to each other
five leaf traces separately enter into the peti later between the basal and middle parts of
田
ole (Fig. 4B). the petiole (Fig. 7D，E ). The connate
5) Taverniera nummulariα(Fig. 7A- F): bundles are，h owever，se parated again at the
Among the four leaf traces，th e additional middle part of the petiole (Fig. 7F).
trace (at) is fused with the adjacent lateral
trace at the node，an d then three traces sepa- 3. Vascular system in the middle part of
rately enter into the petiole(Fig. 7B). The petiole
vascular system at the petiolar base were Cross sections of the middle part of peti-
composed of am edian and two lateral ole，th at is，m id length between the petiolar
242 植物研究雑誌第74巻第4号 平成11年8月
Fig. 8. Diagrams showing six types of petiolar vascular patterns in Hedysarum and
related genera. Hatched and dotted areas show xylem and sclerenchyma，re spec
目
tively. mb，m edian bundle; vb，ve ntral bundle. See text for explanation.
base and the first 1eaflet pair，w ere observed Multicaulia)，a nd H. ferganense (subgen.
in 17 species of Hedysarum，C orethroden- Gamotion sect. Subacaulia).
dron scoparium，S trαcheya tibetica and Type D: Vascular system with the ventral
Taverniera nummularia (Appendix 1.2). In bundles (vb) in addition to the bundles of
this study，t he vascular system of petiole Type C-Hedysarum micropterum (subgen.
was classified into six types according to Gamotion sect. Crinifera)，a nd H. falconeri
fused or free vascular bundles and presence (subgen. Gamotion sect. Gamotion).
or absence of median and ventral bundles Type E: Vascular system of ‘U'-shaped，
(Fig. 8，T able 1). composed of segmented bundles without
Type A: Vascular system formed by three forming al arge median bundle-He dysarum
separated bundles of almost equal size- coronarium and H. glomeratum (subgen.
Hedysarum spinosissimum (subgen. Hedysarum)，S tracheya tibetica，T averniera
Hedysarum). nummularia.
Type B: Vascular system formed by three Type F: Vascular system with the ventral
bundles almost fused in an arc-Hedysarum bundles in addition to the bundles of type
monophyllum (subgen. Gamotion sect. E-Corethrodendron scoparium，H edysarum
Subacaulia). fruticosum subsp. mongolicum and H.
Type C: Vascular system of ‘U' -shaped multijugum (subgen. Heteroloma)，a nd H.
or arced，c omposed of al arge median membranaceum (subgen. Gamotion sect.
bundle (mb) and several small lateral seg- Membranacea).
ments-Hedysarum macranthum (subgen.
Gamotion sect. Crinifera)，H . hedysaroides， 4. Bundle-sheath extention in the leaflet
H. inundatum，H . sikkimense，a nd H. The bundle-sheath extention of leaflet
vicioides var. japonicum (subgen. Gamotion blade was observed in 36 species of
sect. Gamotion)，H . brachypterum and H. Hedysarum and related genera such as
gmelini (subgen. Gamotion sect. Corethrodendron，S tracheya and Tavernierα
，
August 1999 Journal of Japanese Botany Vo .l74 No. 4 243
Figs. 9-12. Cross-sections of lateral veins in leaf blades (9，1 0) and surface views of trichome on
abaxialleaf surface (11，1 2) of Hedysarum. 9. H. vicioides var. japonicum，a 町owindicating bundle-
sheath extension. 10. H. coronarium，s howing no bundle-sheath extention. 11. H. fergαnense. 12.
=
H. coronarium. Scale bars 50μm (9，1 0)，1 0μm(11，12).
(Appendix 1.3). The leaflet blade is distinctly thinner in
In the cross section of leaflet blade，t he sect. Gamotion than other infrageneric
bundle-sheath extention which is ap late of groups of Hedysarum and other genera.
ground tissue extending from ab undle Therefore，t he presence of bundle-sheath
sheath to the epidermis in al eaf (Wylie extention is 1ikely to associate with the
1952，E sau 1977) was observed along the thickness of leaflet blade.
lateral veins of leaflets only in the species
of sect. Gamotion of Hedysarum (Fig. 9). 5. Epidermis of the leaflet
Because the cells of the bundle-sheath Hairs on the leaflet surface were similar
extention reach to the epidermis，th e epider- in morphology among all 36 species ob-
mal cells along the lateral veins are differ- served in the present study (Appendix 1.3).
ent in shape from those of other parts (Fig. Striate sculpture of cuticles and protuber-
13). Therefore the lateral veins become con- ances were observed on the surface of hairs
spicuous from surface view in the species (Figs. 11，12 ). The hairs on the leaf surface
with bundle-sheath extention (Table 1)，al - showed variation in distribution among in-
though the conspicuousness of the lateral fra-or intergeneric groups. The epidermis of
vein was variable among individuals in H. leaflets was densely covered with hairs in
pseudoastragalus and H. sikkimense in sect. sections. Crinifera，M ulticaulia and
Gamotion. On the contrary，th e lateral veins Subacaulia of Hedysarum subgen.
are obscure in the species without those Gamotion，w hile it was glabrous or slightly
(Figs. 17，1 9). pubescent in sect. Gamotion of subgen.
244 植物研究雑誌第74巻第4号 平成11年8月
Figs. 13-18. Adaxial surface views of leaflets of Hedysarum. 13. H. sikkimense var. megalanthum，
showing conspicuous lateral vein from surface view. 14. H. micropterum，s howing the shape of
each epidermal cell hardly distinguished. 15. H. subglabrum，s howing the shape of each epider-
mal cell hardly distinguished. 16. H. lehmannianum，s howing the shape of each epidermal cell
hardly distinguished. 17. H. membranaceum，s howing obscure lateral veins from surface view. 18.
H. coronarium，o bserved with SM-CRU crio-system，s howing the shape of each epidermal cell
=
well distinguished. Scale bars 50μm.
August 1999 Journal of Japanese Botany Vo .l74 No. 4 245
Figs. 19-22. Adaxial surface views of leaflets of Hedysarum and related genera. 19. H. fruticosum
subsp. mongolicum，s howing obscure lateral veins from surface view. 20. Corethrodendron
scoparium，s howing the shape of each epidermal cell well distinguished. 21. Taverniera
nummularia，s howing the shape of each epidermal cell well distinguished. 22. Stracheya tibetica，
showing the shape of each epidermal cell well distinguished. Scale bars =5 00μm (19)，5 0μm
(20-22).
Gamotion and subgenera Hedysarum and from surface view in other groups (Figs. 13，
Heteroloma of Hedysarum，C orethroden 17-22).
噌
dron，S tracheya and the most species of
Taverniera. Discussion
Cuticular membranes in the leaflet epider- Three nodal types，un ilacunar，tr ilacunar，
mis were well-developed in such groups as and mutilacunar types，w ere recorded by
sections Crinifera，民1ulticauliaand Watari (1934) in Leguminosae. The
Subacaulia of Hedysarum (Figs. 14-16， trilacunar type was most common in the
Table 1). Because the cuticular membranes family，b ut the unilacunar type was only
were well-developed even in the area be- recorded in some species in tribe Genisteae，
tween the epidermal cell walls (cuticular and the multilacunar type was sporadically
flange; Stace 1965)，th e shape of each epi- found in subfamilies Caesalpinioideae and
dermal cell of those species could not be Papilionoideae (Watari 1934). The trilacunar
distinguished from surface view by SEM. type was inferred to be the more primitive
On the contrary，it was cleary distinguished type in Leguminosae (Polhill 1981 a). This