Scanning Electron Microscopy Observation on Early Ontogeny of the Flower of Camellia japonica L.

5 Pages·1991·0.45 MB·English

by  Mitsuko Sugiyama

植物研究雑誌
J. Jpn. Bot.
66: 295-299 (1991)
Scanning Electron Microscopy Observation
on Early Ontogeny of the Flower of Camellia japonica L.
恥1itsukoSUGIYAMA
Saitama Women's Junior College
2011，K amihirose，S ayama，S aitama，3 50・13JAPAN
SEMによるヤブツバキの花の初期発生の観察
杉山明子
埼玉女子短期大学 350-13狭山市上広瀬 2011
(Received on May 11，1 991)
The early ontogeny of af lower of Camellia japonica was studied with SE恥ιTheflower is born
on the axil of the lowermost bud scale of the winter bud. The spiral initiation of perules takes place
in early summer，a nd three carpels and aw horl of 11 to 13 stamens are followed to arise in the
simultaneous sequence at the floral apex. The multistaminate androecium is further initiated in the
centrifugal manner and three layers of stamen rings finally arise around the gynoecium. The gynoecium
initiates as three separated mounds at the tip of the floral apex but in the later development they are
united to form as 戸lcarpousgynoecium.
Introduction tions were found in Theales (sensu Cronquist)，a nd
The ontogenetical sequence of androecium the androecium did not show centrifugal develop-
whether the initiation to be centrifugal or centri- ment in both Actinidiaceae (Heel 1987) and
petal has been considered to be significant on the Ochnaceae (Pauze and Sattle 1978).
classification of Dillenudae (Cronquist 1981). Payer The present study was dealt with genus Camellia
(1857) made brief observation on flowers of Visnea and focused to provide further comprehensive
mocanera，T heαviridis，G oldonia lasiαnthus and ontogenetical data for better understanding of so
，
Ternstroemiα， peduncu laris，組 dfirst showed the called “Guttiferalean Complex" (Cronquist 1968).
centrifugal initiation of the androecia in the
Theaceae. Erbar (1986) studied the floral develop- Materials and methods
ment of Stewartia pseudocamellia (Theaceae) and The young flower buds of Camellia japonica
reported that the fascicles of androecial pri- were collected in July to January 1985 through
mordium were initiated in the spiral order，b orn 1989. All the materials were cultivated at the
epipetally in the five clusters and located oppositely Botanical Gardens，U niversity of Tokyo. The
to five petals. Likewise in this species the initia- dissected young flowers were killed and fixed in
tion of each stamen was reported to be centrifugal FAA( Sass 1958)，d ehydrated in an ethanol series
within each fascicle. Ont he other hand the excep- followed by critical point drying in liquid carbon
今ゐny
296 植物研究雑誌第66巻第5号 平成3年10月
dioxide. The individual floral primordia in varied 2).
developmental stages were mounted on stubs， Prior to the initiation of androecium and
coated with gold and observed on aH itachi S-405 gynoecium，th e floral apex becomes broadly con-
Scanning Electron恥1icroscope. The electron caveσig. 3). After the innermost perule (plin Fig.
micrographs were taken on Fuji-SS 6x 7 s heet 2) has been initiated the humps of stamen and
film. carpel initials become visible in the central region
The author expresses her cordial appreciation of the concaved floral apex (Fig. 4). These stamens
to Dr. Takasi Yamazaki，B otanical Gardens， and carpels initiate simultaneously and the earliest
University of Tokyo for reading the manuscript stamen primordia arise in aw horl of about 11-13
and to Dr. Noboru Hara，P rofessor of Biology， humps surrounding three carpel primordia.
College of Arts and Science，Un iversity of Tokyo Following the initiation of the inner staminal
for giving her opportunity to use the SEMf acility， whorl，fu rther androecium is successively produced
and to Botanical Gardens，Un iversity of Tokyo for in the centrifugal manner so that the polyandrous
supplying the materials for her present study. concentric whorls surround the gynoecium at
maturation (Fig. 5，6) .
Observations Three carpel primordia elongate longitudinally
The flowsof Camellia if.ψonica are subtended as ar esult of intercalary growth and each remains
ぽ
by the lowest bud scales of av egetative winter bud still independent at this developmental stage (Fig.
born on either axil or terminal. A single flower per 8). Later the carpel primordia become united at
bud is common but two flowers may be born on the base but remain free to the tips. The basal
a single axillary bud. At the base of a short margillS of the individual carpels are curved inward
peduncle，tw o smaller bracteoles are located at the to form septa separating the locules (Fig. 8). When
right angle to the bract. The floral appendages訂e the flower is matured the syncarpous gynoecium
consisted of 8t o 13 greenish sepaloid perules，5 has three free stigmata (Fig. 9).
to 7p etaloid perules，mu ltistaminate androecium In the mature flower of C. japonica the
and three carpelate gynoecium forming united androecium is obviously epipetalous，h owever，
ovary. At the anthesis the petaloid perules are multistamens enot initiated on the inner perules
紅
slightly connated at the base. Stamens are fused but directly incepted on the floral apex in the early
basally and adnated to the base of inner perules. stage of development.
The floral appendages are initiated in as piral
order and the inner five ethe petaloid perules Discussion
訂
(PI-P5) whereas the outer ones are the sepaloid The current study is ap art of detailed observa
舗
(P6 to P9 are only shown in Fig. 1). The perules tions on the flower of the genus Camellia to report
being incepted in the helical sequence，th e floral the early ontogeny of floral appendice and further
apex is reduced in size and androecium and paper on the floral vascularization will be forth-
gynoecium initiation is followed in the later commg.
development stage. The inner perules (P l-P5) e The flower of so-called “Guttiferalean Com-
紅
successively initiated in the spiral sequence on the plex" (Cronquist 1965) is characterized to have a
irregular pentagonal floral apex along its rim and centrifugal androecium and a tendency to be
to be petaloid in nature in later development (Fig. stnenfascicles (Cronquist 1981). Although both
出
October 1991 Journal of Japanese Botany Vol. 66 No. 5 297
Figs. 1-9. SEM observation on ontogeny and development of the f10wer of Camellia japonica. 1-2: Perule initiation.
1. Petaloid perules are initiated but the innermost one (Pl) is not yet appeared. Collected in July. 2. Five petaloid
perules (P 1-P5) eincepted forming ap entagonal rim around the f10ral apex. Collected in July. 3. Concaved f10ral
紅
apex showing no sign of the androecium nor gynoecium initiation at this stage. Collected in July. 4-9: Inception of
androecium and gynoecium. 4. Both initiations take place simultaneously showing the androecium in ae xternal ring
and the gynoecium inside. The arrow heads indicate the independent carpel initiation. Collected in July. 5. Independent
development of the gynoecium. Collected in July. 6. The androecium is initiated and developed centrifugally. The
bases of three carpels are marginally united to form as yncarpic gynoecium. Collected in August. 7. Three whorls
of the stamen ring are formed after the centrifugal initiation of androecium. Collected in August. 8. The upper part
of each carpel elongates to differentiate free styles. Collected in September. 9. Each stamen is differentiated into the
anther and filament while styles remain free on the gynoecium. Collected in November.
PI-P9: Perules. The smaller figures for petaloid and the larger for separoid. FA: Floral apex. C: Carpel. Scale bars
are 5μm for Figs. 1-8，a nd 50 μmf or Fig. 9.
“Woody Ranalean complex" and Rosidae have earlier studies on the Guttiferalean Complex were
polyandrous flower the current taxon has been much devoted to this point. Payer (1857) was the
clearly set off from these two taxa in this respect. first to describe ac entrifugal androecium in genera
The Woody Ranalean Complex had the spiral of Thea，V isnea and Gordonia，w hereas Corner
androecium and Rosidae the centripetal. (1946) was first to point out the phylogenetical
The androecial initiation has been drawn the significance on the ∞ntrifugal development. Erbar
primary interest for those previous students and (1986) studied floral ontogeny of Stewαr，itα
298 植物研究雑誌第66巻第5号 平成3年10月
pseudocamellia in the Theaceae and showed that primordium was subdivided to give rise to
5b ulges of stamen fascicle primordia initiated in secondary stamen primordia in ac entrifugal way
the spiral order opposite to 5p etals but individual and showed the concentric whorls of androecia.
stamens arose on each st出nenfascicle primordium Pauze and Sattler (1987) studied and depicted
in the centrifugal sequence，w hich supported the centripetal initiation of androecium in the
phylogenetical value in the stamen development to Ochnaceae.
the systematics 但rbar1988). The ontogeny of the perianth member (perule)
Un like S. pseudocamellia the stamen primordia in the genus Camellia showed the spiral sequence
of C. jlψonica are initiated first in ar ing on the and result was well agreed with Erbar's observa-
concaved floral apex not forming stamen fascicles tion，s he (1986) also reported the epipetalous
(Fig. 5). The manner of androecial ontogeny wぉ stamen fascicle in S. pseudocamellia. The present
well agreed to Payer's earlier observation on Thea species shows as 泊lilarflower structure at the
and Gordonia. In the later development of C. anthesis that the androecium attached at the base
japonica the concentric androecial rings are laid of the connate inner perules. In C. )ψonica the
centrifugally on the concaved floral apex so as to epipetalous stamen could be as econdary pheno-
form af ew layers of concentric multistaminate menon as ar esult of the multistaminate condition
whorls surrounding the carpel initialsσigs. 7-9). and of the spatial problem between the gynoecium
Eyde (1975) has summarized floral anatomy on and the rim of inner perules. The centrifugal
the bases of angiosperm phylogeny and reviewed stnenis ac onversion of developmental sequence
町
Leins' proposal (1971) for the scheme of andro- from acropetal to basipetal，a nd it may be caused
ecium phylogeny. Leins speculated that the centri- by the spatial limitation for multistamens on the
petal androecium occurred with convexed floral narrow concaved floral axis. There is ad rastic
meristem and the centrifugal with concaved. The discontinuity in the ontogeny of floral apex，a nd
floral apex in C. japonica，h owever，is concaved perules being developed in the spiral acropetal
but not convex as Leins had envisioned the evolu- sequence but the androecium in the whorled and
tionallines on polyandrous dicotyledons. Although centrifugal (Figs. 1-2，5 -6). Our present know-
Leins' proposal is suggestive，it is not appropriate ledge is insufficient for near related taxa and
to discuss phylogeny with the current limited in- extensive studies would be necessary for better
formation. Although Erbar (1986) has suggested understanding on this problem.
the complex centrifugal androecia to be archaic， The gynoecial development is started with three
further study would be needed for the phylo- separate bulges in the center of the concaved floral
genetical evaluation whether the concentric ring of apex in C. japonica (Fig. 4). Their initiation takes
polymerous stamens advanced，or the fasciculate place simultaneously with that of the innermost
spiral archaic. androecial whorl. The three individual carpels are
The other families in Theales were studied on later formed into as yncarpic gynoecium.
the floral development of particular interest on 恥1uchhas been written on the centrifugal
stamen initiation. Heel (1987) studied the floral stamen development in Dilleniales and i臼 allied
development of the Actinidiaceae and elucidated taxa. Recent study in the Actinidiaceae但eelI987)，
that in Actinidia chinensis stamen primordia were and in the Ochnaceae (Pauze and Sattler 1978)
incepted as as ingle androecial whorl then each have opposed to the centrifugal stamen develop-
October 1991 Journal of Japanese Botany Vol. 66 No. 5 299
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characterizing the Dilleniidae. The vascular 一一一一一 1975.Die Beziehungen zwischen multi-
anatomy of the flower and independent initiation staminaten und einfachen Androeceen. Bot.
of syncarpic gynoecium may provide better Jahrb. Syst. 96: 137-231.
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pと:ted' Ochnααtropurpureα. Can. J. Bot. 56:
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ヤブツバキの花の器官発生の初期を観察した.花
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訂
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