Table Of Content植物研究雑誌
J. Jpn. Bot.
74: 212-222 (1999)
Cork Layer Development and Cuticle Thickening in
Stems of the Genus Magnolia Subgenus Yulania
Susumu TERABAYASHI，M asami HIGUCHI and Minoru OKADA
Tsumura Central Research Laboratories，T sumura & Co.，
3586 Yosiwara，Am i-machi，In ashiki-gun，Ib araki，30 0-1192 JAPAN
(Received on December 16，1 998)
Cork layer developrnent and cuticle thickening were exarnined in sterns of the
genus Magnolia subgenus Yulania. Three types of stern anatomy were distinguish-
able. The first type found in M.αcuminata，M . heptapeta，M . quinquepeta and M.
tomentosa is characterized by the rapid developrnent of ac ork layer between cortex
and epiderrnis and the thin cuticle. The second type is observed only in M.
praecocissima. In this species cork layer developrnent is rather slow and the cuticle
becomes thick. The third type found in M. salicifolia (and presurnably in M. biondii)
is characterized by very slow developrnent of ac ork layer and by at hick cuticle.
Key words: Magnolia，st ern，a natorny，c ork layer，c uticle
The genus Magnolia subgenus Yulania is Zhao et al (1986)，a nd Wue t al (1991)，a nd
composed of Sect. Yulania，S ect. Buergeria it was revealed that floral buds of Mαgnolia
and Sect. Tulipastrum (Dandy 1978). Floral species used as Xinyi are distinguishable
buds of many species attributed to this sub- from each other by anatomical features.
genus，s uch as M. amoena Cheng，ル1. Terabayashi and Okada (1991) examined the
biondii Pamp.，M . heptapetα(Buchoz) anatomy of stems bearing floral buds. The
Dandy (= M. denudαtαDesr.)， M. results given here are that cuticle thickness
praecocissima Koidz. (= M. kobus DC.)，M . in the stems beneath floral buds varies
quinquepeta (Buchoz) Dandy (= M. among species and that cork layers are
liliflora Desr.)， M. salicifolia (Maxim.) present in some species but absent in others.
Siebold & Zucc.，M . sprengeri Pamp. and In order to gain ab etter understanding of
others are called Xinyi (辛夷)and have variation of stem anatomy in the genus Mag-
been used mainly for treatment of inflam- nolia subgenus Yulania，it is highly neces-
mation and pain in traditional Sino-J apanese sary to investigate the stem anatomy from a
medicine (Song 1984，M inistry of Health developmental viewpoint. In this article cork
and Welfare 1989，I nstitute of Materia layer development and cuticle thickening
Medica Chinese Academy of Medicinal were observed in several species of subge-
Sciences et al. 1994，N a mba 1994，C hinese nus Yulania and compared among the spe-
Pharmacopoeia Committee of Ministry of cles.
Public Health of the People' sR epublic of
China 1995). Pharmacognostic studies on Materials and Methods
Xinyi were made by Kimura et al. (1961)， Sources of plant material used in this
-212-
August 1999 Journal of Japanese Botany Vo .l74 No. 4 213
Table 1. Magnolia species used in this study
Species Individual No. Source Voucher
Magnoliααcuminata - Cult. Ushiku，l baraki Terabayashi 1342
a
q Cult. Ush iku，lb araki Terabayashi 1343
h，
M. biondii t Cult. Ami，lb araki Terabayashi 1411
I
司 Cu1t. Ami，lb araki Terabayashi 1412
4
M. heptapeta 1 Cult. Ushiku，lb araki Terabayashi 1209
1
(= M. denudata) 勺 Cult. Ami，l baraki Terabayashi 1207
L
4 Cult. Ami，l baraki Terabayashi 1208
3
M. praecocissima 2 Cult. Ushiku，l baraki Terabayashi 1345
1
(= M. kobus) フ Cult. Ushiku，lb araki Terabayashi 1344
-
1 Cult. Ami，l baraki Terabayashi 1346
u
A斗 Cult. Ami，l baraki Terabayashi 1115
ζJ Cult. Amakubo，T sulくuba，lbaraki Terabayashi 1356
M. quinquepetα ' Cult. Ushiku，lb araki Terabayashi 1350
I
(= M. liliflora) 司， Cult. Ush iku，l baraki Terabayashi 1349
L
3司 Cult. Ami，l baraki Terabayashi 1203
A Cult. Ami，l baraki Terabayashi 1204
斗・
M. salicifolia 1 Cult. Amakubo，T sukuba，lb araki Terabayashi 1113
1
司， Cult. Amakubo，T sukuba，lb araki Terabayashi 1114
L
M. tomentosa S Cult. Ushiku，lb araki Terabayashi 1347
I
(= M. stellata) 4司 Cult. Ushiku，l baraki Terabayashi 1111
3今 Cult. Ushiku，l baraki Terabayashi 1202
Voucher specimens are deposited in the herbarium of Tsumura Central Research Laboratories.
study are listed in Table 1. Reference about 20μm thick，a nd stained with aceto-
sources for the scientific names are Dandy methyl green. Before staining some samples
(1978) and Ueda (1985，1 986). The trees were bleached with Eau de Javell.
examined are cultivated and old enough to
bear flowers，th ough trees of M. biondii bore Results
no flowers because of their young age. The In the seven species examined the follow-
collection of stem materials was done twice ing features were observed in common. In
or 3t imes am onth，o btaining 2t o 3s tems middle to late April vegetative buds unfold
in each collection. For critical comparisons and new shoots appear. They elongate and
we observed transections from the basal re- show as econdary growth producing xy lem
gion of current-year stems in M.αcuminata and phloem. Three types of cork layer de-
(L.) L.，M . heptapetα，M . quinquepeta，a nd velopment and cuticle thickening were dis-
M. tomentosa Thunb. (= M. stellata tinguishable in stems.
Maxim.)，c urrent-year and one-yearold The first type found in Magnolia
喧
stems in M. praecocissimα，a nd currentyear， acuminαta，M . heptapeta，M . quinquepeta
四
one-year-old and two-year-old stems in M. and M. tomentosa is characterized by the
salicifolia and M. biondii. Transections of thin cuticle and the rapid development of a
stems of the second internode of each year cork layer (Figs. 2-13). A cork cambium
were cut as shown in Fig. 1f or the reason composed of radially flattened cells with
that the first internodes are often too short thin walls usually occurs at several points
to cut properly. Transections were made at between the cortex and epidermis and gives
214 植物研究雑誌第74巻第4号 平成11年8月
and M. quinquepeta has the thinnest cuticle;
4.5-6(-7.5)μminM.αcuminata，( 2-)2.5-
4(-4.5)μm in M. heptapeta，(1 .5-)2.5-3μm
in M. quinquepeta and (2.5-)3-5μminM.
tomentosa (Fig. 28). In August most of cur-
rent-year stems cease their elongation and
are terminated by dormant vegetative or flo-
ral buds. The stems are pale green and pu-
bescent (but glabrous only in M.
quinquepeta )at the terminal region，p ale
green and pubescent to brown and glabrous
at the middle region，a nd brown and gla-
brous at the basal region. The change of
B
color and texture of stem occurs earlier on
the sunny surface than on the shady surface.
The region of stem where cork layers are
observed in transections is brown in color.
This is due to the brown tannic substances
accumulated in cork cells. Also it is often
C
observed that the initiation of cork cells is
preceded by the accumulation of brown tan-
nic substances in epidermal cells (Fig. 29).
①
The second type is observed only in M.
pαecocissima (Figs. 14-17). In this species
1i
Fig. 1. Diagrammatic illustration of ay oung Mag- new shoots arise from vegetative buds in
nolia shoot. Arrows (1-3) indicate positions late April as in the species of the first type.
where transections were cut and observed. A:
A cork layer appears in late May in af ew
cuent-yearstem; B: one-year-old stem; C: two-
汀 samples，b ut in early July in most samples.
year-old stem; L: leaf; N: node; SA: shoot apex.
Also in this species ac ork layer starts as a
discontinuous ring around the stem. In Au-
rise to cork cells outside. Thus ac ork layer gust the cork layer encircles more than half
starts as ad iscontinuous ring which appears of the cortex in cross sectional view but not
in middle May to early June in M. heptapeta completely. It is noteworthy in this species
and in late May to early July in M. that the cork layer of the cuent-yearstems
町
acuminata，M . quinquepeta and M. is partially undifferentiated even at the end
tomentosa (Figs. 3，6 ，9 ，1 2，26 ). In the spe- of the growing season (late August) (Figs.
cies of this type，a c ork layer develops rather 14-17，27 ). During the growing season of
rapidly and more than one layer of cork the second year the cork layer of one-year
cells completely encircle the cortex in cur- old stems continues to develope and finally
rent-year stems in August (Figs. 4，7 ，1 0，13 ， encircles completely the cortex (Figs. 17，
27). In new growth the cuticle gradually 27). In the second type the cuticle thickens
thickens and remains almost constant in more slowly and it becomes thicker than
thickness after about 30 days in M. that in the first type. The cuticle gradually
acuminata and about 60 days in other spe- thickens and attains almost constant thick-
cies (Fig. 28). In the four species of the first ness of 10-13(-15)μm，in about 100 days
type M. acuminata has the thickest cuticle after bud unfolding (Fig. 27). In August or
August 1999 Journal of Japanese Botany Vo .l74 No. 4 215
Figs. 2ー7. Magnolia acuminata and M. heptapeta. Figs. 2-4. M. acuminata. Transections of cur-
rent-year stems collected on May 31 (Fig. 2)，J une 19 (Fig. 3) and July 4( Fig.4) in 1993. Fig.
2. A young stem newly arising from av egetative bud. Cambium active but cork layers not
differentiated yet. Fig. 3. Thin cuticle visible，c ork layer partially differentiated. Fig. 4. Two
layers of cork cells encircling completely the cortex. Figs. 5-7. M. heptapeta. Transections of
currentyearstems collected on April 24 (Fig. 5)，M ay 29 (Fig. 6) and August 9( Fig. 7) in
四
1993. Fig. 5. A young stem newly arising from av egetative bud. Cambium active but cork
layers not differentiated yet. Fig. 6. Thin cuticle visible，c ork layer partially differentiated. Fig.
7. Two-three layers of cork cells encircling completely the cortex. Transections bleached and
stained with aceto-methyl green in Figs. 3，4 ，6 a nd 7. cu: cuticle; cx; cortex; ep: epidermis;
fb: fiber bundle; h: hair; id:sclerified idioblast; kl: cork layer; m: pith; oc: oil cell; ph: phloem;
xy: xylem. Scale bars are 100μm in Figs. 2，3 ，5 a nd 6，5 00μm in Figs. 4a nd 7.
216 植物研究雑誌第74巻第4号 平成11年8月
Figs. 8-13. Mαgnolia quinquepeta and M. tomentosα. Figs. 8-10. M. quinquepeta. Transections
of current-year stems collected on June 2( Fig. 8)，J une 19 (Fig. 9) and August 29 (Fig. 10)
in 1993. Fig. 8. A young stem newly arising from av egetative bud. Cambium active but cork
layers not differentiated yet. Fig. 9. Thin cuticle visible，co rk layer partially differentiated. Fig.
10. Two-three layers of cork cells encircling completely the cortex. Figs. 11-13. M. tomentosa.
Transections of current-year stems collected on May 9( Fig. 11)，J une 15 (Fig. 12) and Au-
gust 26 (Fig. 13) in 1993. Fig. 11. A young stem newly arising from av egetative bud. Cam-
bium active but cork layers not differentiated yet. Fig. 12. Thin cuticle visible，c ork layer
partially differentiated. Fig. 13. Two-three layers of cork cells encircling completely the cor-
tex. Transections bleached and stained with aceto-methyl green in Figs. 9，1 0，1 2 and 13. cu:
cuticle; cx; cortex; ep: epidermis; fb: fiber bundle; id:sclerified idioblast; kl: cork layer; m:
pith; oc: oil cell; ph: phloem; xy: xylem. Scale bars are 100μm in Figs. 8，9 ，11 and 12，5 00
μmi n Figs. 10 and 13.
August 1999 Journal of Japanese Botany Vo .l74 No. 4 217
September most of current-year stems cease for critical comparisons of anatomical fea-
their elongation and are terminated by dor- tures. Preliminary observations in this spe-
mant vegetative or floral buds. At the end of cies showed that it belongs to the third type.
the growing season most parts of current- A cork layer is not or only al ittle differen-
year stems are green or pale green and tiated in current-year stems (Figs. 22，2 3，
smooth but partially brown and rough at the 27). In the second year，a c ork layer devel-
basal region. In August of the second year ops and partially encircles the cortex (Figs.
one-year-old stems are mostly brown in 24，27 ). In the third year，a c ork layer com-
color but partially green at the terminal and pletely encircles the cortex (Figs. 25，2 7).
the middle regions. The cuticle of this species becomes about
The third type observed in Mαgnolia 12.5-15(-16)μm in thickness (Fig. 28). In
salicifolia is characterized by the remark- August currentyearstems are green and
四
ably slow development of ac ork layer and smooth throughout their length. At the end
the very thick cuticle (Figs. 18-21). In M. of the growing season one-year-old stems
salicifolia new shoots appear in late April as are brown on the sunny surface but still
in the species of the first and the second green on the shady surface at the basal re-
types. A cork layer is hardly observed in the gion as in M. salicifolia. Two-year-old
first year，a lthough the cambium between stems are brown as aw hole but remain
phloem and xylem is active (Fig. 19). In the green partially on the shady surface.
second year，a c ork layer starts to differen-
tiate outside the cortex. Different from the Discussion
second type (M. praecocissima)，c omplete Terabayashi and Okada (1991) reported
encircling of the cortex by the cork layer is that the genus Magnolia subgenus Yulania
quite rare in one-year-old stems of the third showed variation in the development of a
type (Fig. 20). In the third year，a c ork layer cork layer and cuticle thickness in current-
is present in every two-year-old stem exam- year stems bearing floral buds. In Magnolia
ined (Figs. 21，27 ). In some of these stems， acuminata，M . heptapeta，M . quinquepeta，
however，th e cork layer has not completely and M. tomentosa cork layers were present
encircled the cortex by the end of the grow- and cuticle was thin. In M. praecocissima a
ing season of the third year (Fig. 27). In the cork layer was present or absent and cuticle
third type，t he cuticle thickens more slowly was thick. In M. amoena，M . biondii and M.
and becomes thicker than that in the second salicゆliacork layers were constantly ab-
type. The cuticle becomes (16一)18-24(-28) sent and cuticle was thick. The present study
μmt hick approximately 150 days after bud on stem development reveals that variation
unfolding (Fig. 28). In M. salic扮liamost of of stem anatomy in the genus Magnolia sub-
current-year stems cease their elongation genus Yulania (Terabayashi and Okada
and are terminated by dormant vegetative or 1991) is caused by different manners of cork
floral buds in August to September. At the layer development and of cuticle thickening
end of the growing season current-year among the species (Stem anatomy was not
stems are green to pale green in color and examined for M.αmoena in the present
smooth in texture. One-year-old stems are study.) As already described above，a c ork
still green but partially brown at the basal layer develops rapidly in M. acuminata，M .
region. Two-year-old stems are brown as a heptapeta，M . quinquepeta and M.
whole but remain green partially on the tomentosa，s lowly in M. praecocissima，a nd
shady surface. remarkably slowly in M. salicifolia and M.
The trees of M. biondii were too young biondii. Cuticle grows less than 7.5μm in
218 植物研究雑誌第74巻第4号 平成11年8月
thickness in M. acuminata，M . heptapeta，M . The grouping of genera defined by the
quinquepeta and M. tomentosa，bu t becomes stem anatomy does not agree to the classi-
more than 10μm in M. praecocissima，a nd fication system proposed by Dandy (1978).
more than 12.5μm in M. salicifolia and M. The species of Sect. Yulania (M. heptapeta.)
biondii. and of those of Sect. Tulipastrum (M.
August 1999 Journal of Japanese Botany Vo .l74 No. 4 219
Figs. 22-25. Magnolia biondii. Transections of currentyearstems collected on April 28 (Fig. 22)
田
and July 25 (Fig. 23) in 1993，on e-year-old stems collected on August 3( Fig. 24) in 1994 and
two-year-old stems collected on August 9( Fig. 25) in 1995. Fig. 22. A young stem newly
arising from av egetative bud. Cambium active but cork layers not differentiated yet. Fig. 23.
Very thick cuticle visible，c ork layer not differentiated yet. Fig. 24. Cork layer partially dif-
ferentiated. Fig. 25. Three-five layers of cork cells encircling completely the cortex，t wo an-
nual rings observed in xylem. Transections bleached and stained with aceto-methyl green in
Figs. 24 and 25. ar: annual ring; cu: cuticle; cx; cortex; ep: epidermis; fb: fiber bundle;
id:sclerified idioblast; kl: cork layer; lc: lenticel; m: pith; oc: oil cell; ph: phloem; xy: xylem.
Scale bars are 100μm in Figs. 22，2 3 and 24，5 00μm in Fig. 25.
Figs. 14-21. Magnolia praecocissima and M. salicifolia. Figs. 14-17. M. praecocissima. Transections of cur-
rent-year stems collected on April 27 (Fig. 14)，J une 27 (Fig. 15) and Aug. 26 (Fig. 16) in 1993 and one-
year-old stems collected on July 27 (Fig. 17) in 1994. Fig. 14. A young stem newly arising from av eg-
etative bud. Cambium active but cork layers not differentiated yet. Fig. 15. Thick cuticle visible，c ork
layer not differentiated yet. Fig. 16. Cork layer partially differentiated. Fig. 17. Three-five layers of cork
cells encircling completely the cortex，o ne annual ring observed in xylem. Figs. 18-21. M. salicザolia.
Transections of current-year stems collected on April 26 (Fig. 18) and July 23 (Fig. 19) in 1993，o ne-
year-old stems collected on August 30 (Fig. 20) in 1994 and two-year-old stems collected on July 23 (Fig.
21) in 1995. Fig. 18. A young stem newly arising from av egetative bud. Cambium active but cork lay-
ers not differentiated yet. Fig. 19. Very thick cutic1ev isible，c ork layer not differentiated yet. Fig. 20.
Cork layer partially differentiated. Fig. 21. Three-five layers of cork cells encircling completely the cor-
tex，t wo annual rings observed in xylem. Transections bleached and stained with aceto-methyl green in
Figs. 16，17 ，2 0 and 21. ar: annual ring; cu: cuticle; cx; cortex; ep: epidermis; fb: fiber bundle; id: sclerified
idioblast; kl: cork layer; lc: lenticel; m: pith; oc: oil cell; ph: phloem; xy: xylem. Scale bars are 100μm
in Figs. 14，1 5，1 6，1 8，1 9 and 20，50 0μm in Figs. 17 and 21.
220 植物研究雑誌第74巻第4号 平成11年8月
'・
4
Fig. 26. Diagrammatic illustrations of cork layer development in Magnolia stems. 1: Cork layer
not differentiated; 2: Cork layer encircling less than half of the cortex; 3: Cork layer en-
circling more than half of the cortex; 4: Cork layer encircling completely the cortex. ep:
epidermis. kl: cork layer.
+ωCJ ・× ・-
aE 4 企 XA 溜AX邑 A ・臥 a
O
• • • •
~ 3 1M ・泊IXX
ω
コてa ・・・ ・・
2
A .. A X A
〉ro、 ・匝】・・・企圃・×・× ・・
ニピ。1 4
L..
υ
Apr.l，93 May 1，93 Jun.l，93 Jul.l，93 Aug.l，93 Sept.l，93
Date
+Zω-' 園田園・・・・ ・ ...-.・.・.・.- .x ・・・ ...
E 4
c.. 薗
o -・...・・・ 田園
x.....
コてω~ 3 ー・ -・×・・ 園く・・・×圃周回 :X".×・・•• • .・・ ・・ ・
包2 P
〉r、ロ 山×・・・ ・・・・×・・.....
。
ゼ 1 刈IIXIIIXI 4X
仁J
Apr.l，93 Aug.l，93 Dec.l，93 Apr.l，94 Aug.l，94 Dec.l，94 Apr.l，9.5 Aug.l，95 Dec.l，95
Date
Fig. 27. Cork layer development in Magnolia stems examined in 1993-1995. Upper :C ork layer
development in M. acuminata (X)，M . heptapeta (....)， M. quinquepeta (+) and M.
tomentosa (.). Lower: Cork layer development in M. praecocissima (.)， M. salicifolia
(+) and M. biondii (X). 1: Cork layer not differentiated; 2: Cork layer encircling less than
half of the cortex; 3: Cork layer encircling more than half of the cortex; 4: Cork layer encir
司
cling completely the cortex. See Fig. 26.
August1 999 Journal of Japanese BotanyV o .l74 No. 4 221
8
μm ×
7 ×
ω~ 6 × × × × 受ו •
豆u 5 ×× × 受 × ×× 、- ×
-:5 4 .× . 臥.・・
ちaω 3 × a• 1. ~ • s .，企
+-' 2 ・a• -企..a--企 企 -•
企
n L
Apr.l，93 May 1，93 Jun.l，93 Ju.ll，93 Aug.l，93 Sept.l，93
Date
30
μ作1 •
一工一Fωυωωωcu品 221550 .'_ s-*長.3・.・ー.s= ・ .. × -A' r.sE •・•'• •・E， 3・1.L.•、久.. ??xE•・!. ・と-.x 予‘t ー•ー ....•~~h .....~• ...~ × s §. .・.・t.・ー・..・~. ー.・..ー~'.~ . ・..‘~ ? v....
一コυ一一v 10 ヵ・•••司 IJ•X .・圃 • ×
υ
5
Apr.l，93 Aug.l，93 Dec.l，93 Apr.l，94 Aug.l，94 Dec.l，94 Apr.l，95 Aug.l，95 Dec.l，95
Date
Fig.28 . Cuticle thickening in Mαgnolia stems examined in 1993-1995. Upper: Cuticle thickening
in M.a cuminatα(X)，M . heptapeta (企，)M. quinquepeta (+) and M. tomentosa (.).
Lower: Cuticle thickening in M. praecocissima (.)， M. salicifolia (φ)a nd M. biondii
(X )
αcuminata and M. quinquepeta) show the
first type. Sect. Buergeria is diverse in the
stem anatomy: M. tomentosa is of the first
type，M . praecocissimαis of the second and
M. salicifolia and M. biondii are of the third.
It is noteworthy that in the species with
thin cuticle ac ork layer develops rapidly
(the first type)，w hile in those with thick
cuticle ac ork layer develops slowly (the
second and the third types). It is af uture
project to make clear the ecological or plant
geographical implications of the different
Fig. 29. Brown tannic substances accumulated in
types of stem anatomy described here.
epidermal and cork cells in Magnolie heptapeta.
cu: cuticle; ep: epidermis; kl: cork layer; oc: oil
The authors are grateful to Prof. Kunihiko
cell. Scale bar is 100μm.
