全 文 ：Floral Organogenesis of Titanotrichum oldhamii (Gesneriaceae)
PAN Kai_Yu , LI Zhen_Yu＊ , WANG Yin_Zheng
(Laboratory of Systematic and Evolutionary Botany , Institute of Botany , The Chinese Academy of Sciences , Beijing 100093, China)
Abstract:　Floral organogenesis of Titanotrichum oldhamii (Hemsl.)Soler., the only species in the genus
and endemic to East Asia , was observed under SEM.We found that the development of calyx , corolla and an-
droecium belongs to pentamerous pattern.They come respectively from primordia of calyx , corolla and androe-
cium , and all differentiated from the flower primordium.The zygomorphism of corolla and androecium is de-
rived from quicker growth of the upper lip of corolla and delay in development of the staminode.Initiation of
sepal primordia and their development are not consistent in order;the order of initiation is from adaxial central
primordium , abaxial two primordia and finally lateral two primordia , while the order of development is first
adaxial central sepal , lateral two and finally abaxial two.Sepals are valvate in flower bud.Initiation of corolla
lobe primordia and their development are consistent in order , i.e.first abaxial central lobe(central lobe of the
lower lip), lateral two(lateral two lobes of the lower lip)and finally adaxial two (two lobes of the upper lip).
The aestivation of corolla is imbricate , and the order from outside to inside is the central lobe of the lower lip ,
lateral two of the lower lip , and finally two of the upper lip or lateral two lobes of the lower lip , two of the up-
per lip and central one of the lower lip.Stamen primordia are alternate to the corolla lobe primordia , with the
anterior two primordia later than the posterior two in initiation;staminode primordium is simultaneous with the
posterior two in initiation , but smaller , and opposite to the adaxial carpel(upper lip of stigma).Compared to
the patterns of floral organogenesis of Rehmannia (Scrophulariaceae), Whytockia and Rhynchoglossum (Ges-
neriaceae), the present authors found that the floral organogenesis is diverse and does not form two distinct
patterns among these four genera.Based on the results we tend to consider that the conventional demarcation
between the Scrophulariaceae and Gesneriaceae using number of ovary locules(two vs one)and placentation(axile vs parietal)is questionable.
Key words:　Gesneriaceae;Titanotrichum ;floral organogenesis
　　The genus Titanotrichum , belonging to the subfamily
Cyrtandroideae in the family Gesneriaceae , forms a mono-
generic tribe , Titanotricheae Yamazaki ex W.T.Wang ,
with a single species , T .oldhamii (Hemsl.)Soler.,
which is endemic to East Asia and distributed in Fujian ,
S.Zhejiang and Taiwan in China , and Ryukyu in
Japan[ 1-3] .
Since Forbes and Hemsley
[ 4]
described this species
in 1890 in the genus Rehmannia(R.oldhamii Hemsl.)
of the Scrophulariaceae with a question marker , its sys-
tematic position has been controversial.Solereder[ 5] es-
tablished a new genus , Titanotrichum , to accommodate
the species , T.oldhami(Hemsl.)Soler.and placed it
into the Gesneriaceae (Cyrtandroideae:Didymocarpeae)
together with Rehmannia.In 1949 Sealy[ 6] considered the
genus Titanotrichum more closely related to Isoloma(=Kohleria)and Naegelia(=Smithiantha)in the sub-
family Gesnerioideae than to the subfamily Cyrtan-
droideae.Burtt[ 7] kept Titanotrichum in Gesneriaceae ,
but removed Rehmannia back to the Scrophulariaceae ,
whereas Kvist and Pedersen
[ 8]
considered the genus under
study more closely related to the Scrophulariaceae than to
the Gesneriaceae.Wang et al[ 1 ,9] established a new
monotypic tribe for the genus , tribe Titanotricheae , in
Gesneriaceae , and arranged the tribe after the tribe
Klugieae.Based on sequences of cpDNA gene ndhF of
the Gesneriaceae , Smith et al[ 10 ,11] was still not certain
of the systematic position of Titanotrichum , considering
that the genus is relatively close to Gesneriaceae , in
which it is more closely related to Cyrtandroideae than to
Gesnerioideae.Observed in the present work was floral
organogenesis of the genus Titanotrichum with the aim of
providing evidence on ontogeny to resolve its phylogenetic
position.
1　Materials and Methods
The material for this study was collected in August of
2000 and 2001 from Yongchun County , Fujian Province ,
China.The voucher , LI Zheng_Yu and ZOU Xiu_Hong
11327 , is preserved in the Herbarium of Institute of
Botany , the Chinese Academy of Sciences(PE).Inf lo-
rescences at different stages of development were fixed in
FAA.After being soaked in 95% alcohol for over 24 h
floral apex was peeled off from the material.The obtained
apex or flower buds were stepwisely dehydrated with abso-
lute alcohol and iso_amlyacetate.The material was critical
point_dried with CO2 , mounted , coated and observed un-
der a SEM Hitachi S_800.Ovaries were fixed in FAA ,
and sections (6 -10 μm in thickness)were prepared
Received:2002-03-26　Accepted:2002-07-08
Supported by the State Key Basic Research and Development Plan of China(G2000046801)and the National Natural S cience Foundation of China(39870056).
＊Author for correspondence.
植　物　学　报　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　
Acta Botanica Sinica　2002 , 44(8):895-902
according to the conventional paraffin method and were
stained with saf rannin_fast green.
2　Results
2.1　Inflorescences
The genus Titanotrichum is a perennial.Rhizomes
possess fleshy scales.Stems are unbranched.Basic unit
of inflorescences is a cyme , on which usually only the ter-
minal flower developed , while lateral ones reduced(Fig.
1), and thus the cyme seems to have a single flower.
However , sometimes both the terminal and one of lateral
flowers developed.A number of cymes formed a reduced
panicle , which appeared racemose.By opening bracts
and bracteoles , flower primordia and flower buds at differ-
ent stages were found irregularly arranged on an inflores-
cence axis , which became nearly pyramidal in shape , and
was covered with multicellular hairs(Figs.2 ,3).
2.2　Floral morphology
A mature flower is of a relatively large bract and 1-
2 bracteoles at the base (Fig.4).Flowers are bisexual ,
zygomorphic , with five nearly equal sepals , corolla in-
fundibuliform_tubular , limb two_lipped , upper lip two_
lobed , lower lip three_lobed;fertile stamens four , all in-
serted at the base of corolla tube , didynamous , one
staminode on adaxial side;anthers two_locular , longitudi-
nally dehiscent , filaments dorsifixed;disc inferior;ovary
superior , one_locular with two parietal placentae , stigmas
two , posterior one minute , anterior one lingulate , entire.
2.3　Initiation and development of calyx primordia
At the top sect of inflorescences collected inmid Au-
gust we found flower buds and cyme primordia with size
getting gradually smaller upwards , and arranged in all di-
rections(Fig.3).When cyme primordia near the top of
inflorescence became oblate and apex flattened with a size
about 51μm in diameter lateral flower primordia could not
be seen(Fig.5).As the terminal flower primordium be-
came spherical and its apex swelled upwards , two bracte-
ole primordia different in size differentiated on lateral
sides and the lateral flower primordia had just appeared
(Fig.2).Subsequently , the bracteole primordia elongat-
ed and flattened , becoming ovate bracteoles(Figs.6 ,7).
The floral apex continued to swell upwards , and one or
two protuberances , whose cells tightly arranged , occurred
at a 90°angle to the bracteoles.They are the abaxial
sepal primordia(Figs.8 , 9).Soon after a smaller rounded
protuberance differentiated on opposite (adaxial) side ,
i.e.adaxial sepal primordium , and then lateral two sepal
primordia arose at inner side of the two bracteoles(Figs.
10 ,11).As the sepal primordia continued to develop ,
adjacent ones united only at the very base.The sepal pri-
mordia flattened , elongated and laterally expanded , grad-
ually becoming separate and ovate sepals in a primary
state in the order:adaxial one , lateral two and finally
abaxial two(Figs.10-12).Sepals continued to elongate
and curved inwards , and gradually covered the centre of
floral apex.Margins of adjacent sepals were close to each
other , and thus calyx aestivation was valvate.From epi-
dermal cells grew rounded and verrucose protuberances ,
which developed into multicellular hairs(Figs.13 ,14).
2.4　Initiation and development of corolla lobe pri-
mordia
When all the sepals had formed but their indumen-
tum had not differentiated , the flower bud reached a size
of 143-200 μm in diameter.By opening such a flower
bud with sepals removed , it could be found that the floral
apex slightly swelled but then flattened , and gradually be-
came pentagonal , 94-125 μm in diameter.As the five
sides swelled upwards simultaneously the five angles alter-
nate to sepals expanded and swelled , forming small
rounded protuberances(Figs.11 ,15), whose top enlarged
rapidly and became corolla lobe primordia in such an or-
der:first abaxial central lobe primordium , abaxial lateral
two and finally adaxial two(Figs.16-19).The pentago-
nal meristem continued to grow and became circular ,
forming an initiative state of corolla tube(Figs.20-23).
The abaxial central primordium first flattened ,
elongated and widened , becoming deltoid(central lobe of
※
Figs.1-20.　SEM observations on morphogenesis of inflorescences and floral organs.1.A cyme , showing the well developed apical flower
and reducing primordium of a lateral flower , ×150.2 , 3.Apical part of an inflorescence , showing floral primordia at different developmental
stages and irregularly arranged.2.×120.3.×48.4.A floral bud , showing a bract , two bracteoles and sepal , ×12.5-9.Initiation of
floral primordium and calyx primordia.5.Apical part of an inflorescence , showing cyme primordia , ×240.6.Showing bracteoles primordia ,
×420.7.Flattening of bracteole primordia , and upward swelling of floral apex , ×240.8.Showing primordia of bracteoles and abaxial two
sepals , ×210.9.Primordia of two abaxial sepals , ×300.10-14.A flower , showing development of sepals.10 , 11.Adaxial sepals , abax-
ial two sepals at early stage , and flattened pentagonal centre of floral apex.10.×150.11.×240.12-14.Sepals at late stage of develop-
ment , showing verrucose protuberances on the dorsal side and valvate aestivation.12.×210.13.×180.14.×120.15-19.A flower ,
showing order of initiation of corolla lobe primordia and stamen primordia.15.Pentagonal floral apex swelling upwards , ×180.16-18.Flo-
ral apex with sepals removed.16.Showing corolla lobe primordia at an early stage , ×240.17.Showing corolla lobe primordial at a later
stage , ×210.18.Initiation of abaxial central corolla lobe primordium and abaxial lateral two.19.Showing primordia of corolla lobes , poste-
rior stamens and staminode , ×210.20.A flower , showing order of development of coroll lobe primordia and fertile stamen primordia:abaxial
central lobe of corolla first flattening , then abaxial two lateral and finally adaxial two;anterior stamen primordia rapidly growing and slightly
larger than posterior stamen primordia , and staminode primordium retarding in development , ×150.
Abbreviations:B , bract;Bl , bracteole;Cb , abaxial lateral lobe primordium of corolla or abaxial lateral lobe of corolla;Cc , abaxial central
lobe primordium of corolla or abaxial central lobe of corolla;Cd , adaxial lobe primordium or adaxial corolla lobe;CY , A cyme primordium;
F , floral primordium or floral apex;Fl , reducing primordium of a lateral flower;I , inflorescence;S , sepal or sepal primordium;Sa , anterior
stamen primordium or anterior stamen;Sb , abaxial sepal primordium or abaxial sepal;Sc , adaxial center sepal primordium or adaxial center
sepal;Sd , adaxial latral sepal primordium or adaxial sepal;Sn , staminode primordium or staminode;Sp , posterior stamen primordium or pos-
terior stamen.
896　 植物学报　Acta Botanica Sinica　Vol.44　No.8　2002
PAN Kai_Yu et al:Floral Organogenesis of Titanotrichum oldhamii(Gesneriaceae) 897　
the lower lip).This was followed by abaxial lateral two
primordia (lateral two lobes of the lower lip), and finally
adaxial two lobe primordia (Fig.21).Therefore , initia-
tion of the primordia and their subsequent development of
corolla lobes were consistent in order.
When the five corolla lobe primordia all differentiat-
ed and became deltoid , they became rounded at the top.
At this time the lobes gradually curved inwards and as the
corolla tube arose high and high they gradually enveloped
the central part of the floral apex.Simultaneously , the
adaxial two lobes grew obviously more quickly than the
abaxial three , and thus corolla zygomorphism appeared(Figs.22-24).
As corolla tube continuously elongated , and corolla
898　 植物学报　Acta Botanica Sinica　Vol.44　No.8　2002
lobes grew , widened and curved inwards , the flower bud
developed into a size of 0.6-1.8 mm in diameter.The
corolla aestivation , as we observed , is imbricate;we saw
from outside to inside the abaxial central lobe , abaxial
lateral two and finally adaxial two (Figs.25 , 26)or the
adaxial two lobes , abaxial lateral two and finally abaxial
central one (Fig.27).Thereafter , when all the floral
parts grew rapidly and the corolla tube reached five times
as long as the limb , the gynoecium and androecium also
elongated up to the corolla limb and the flower is ready to
open.
2.5　Initiation and development of androecium pri-
mordia
Initiation of stamen primordia took place later than
that of corolla lobe primordia and they were alternate to
the latter.In between the adaxial two lobe primordia and
the abaxial lateral two lobe primordia and in between
adaxial two lobe primordia but more inwardly occurred
three oblate protuberances.They are two posterior stamen
primordia and one staminode primordium(Fig.17).Fol-
lowing enlargement of the three primordia , the other two
small rounded protuberances occurred on lateral sides of
abaxial central corolla lobe primordium but closer to the
centre of the floral apex.These were anterior two stamen
primordia (Fig.19).When the corolla tube enlarged in
height and width and reached a diameter of 60 μm , the
corolla lobe primordia began to differentiate , and the sta-
men primordia continued to enlarge into spherical.At this
time , the anterior stamen primordia(ca.60μm in diam-
eter)were slightly larger than the posterior two (ca.54μm in diameter), while the staminode primordium main-
tained the smallest (ca.36 μm in diameter)(Figs.20 ,
21).As the corolla lobe primordia flattened and curved
inwards , the fertile stamen primordia flattened and elon-
gated into nearly spherical(Figs.22-24), and then hor-
izontally elongated.Soon they sank into a slit at surface
and constricted in the middle.Thus anther locules and
connective differentiated , and the prototype of anthers had
formed , becoming oblong , 300μm in length and 165 μm
in width , whereas the staminode primordium developed
much later and grew slowly , becoming rectangular , only
54μm in length and 41μm in width (Fig.32).
As anther locules elongated right downwards and
widened , the sunken slit became even more remarkable
and anther locules ellipsoid(Fig.33);the staminode flat-
tened into lamellate , 0.6 mm long , without an obvious
filament(Fig.34).Filaments of the fertile stamens de-
parted from near the base of corolla tube and were dorsi-
fixed.Owing to relatively slow growth of the anterior sta-
mens the four fertile stamens became didynamous and free
at the top (Figs.35-37).
2.6　Initiation and development of gynoecium pri-
mordia
The gynoecium primordium was derived directly from
the central meristem of the pentagonal floral apex.When
the corolla lobe primordia flattened and curved inwards ,
and the stamen primordia began to differentiate , the cen-
tre of the floral apex swelled upwards and subsequently
sank at the very centre , forming a arched depression(Fig.22).The depression continued to sink and enlarged
into a nearly orbicular hole , which divided the central
part of the pentagonal floral apex into two unequal meris-
tem regions , with the abaxial region much larger than the
adaxial one , and two carpel primordia thus began to dif-
ferentiate (Figs.23 , 24 , 28).As the carpel primordia
widened below and arose upwards above , and the meris-
tem in the hole continuously differentiated , the adaxial
and abaxial sides of each carpel primordium grew at dif-
ferent rates and thus they became arched(Figs.29-31).
When the two carpel primordia enlarged at the base and
grew upwards , they became conical and gradually con-
stricted into unequally two_lipped at the top.At this
time , ovary and stigma had formed , but style had not ini-
tiated yet(Figs.32 ,33).
As verrucose protuberances occurred on the outer
wall of the ovary and gradually developed into multicellu-
lar hairs , the gynoecium continued to constrict at the top ,
and due to intercalary growth the top grew upwards rapidly
up to the corolla limb in height , forming a cylindrical
style (Figs.34 ,35 ,38).In a transverse section , margins
→
Figs.21-34.　SEM observations on morphogenesis of inflorescences and floral organs.21.Continuous flattening and elongating of abaxial
central lobe of corolla, four fertile stamens primordia and delayed development , and staminode primordium , ×210.22-24.Inwards curving
corolla lobes;adaxial lobes slightly longer than the others , corolla tube , fertile stamens starting flattening , central arched slit(hole)of flower
primordium dividing meristem into two unequal regions , and two carpels at early stage of development.22.×120.23.×132.24.×90.
25 , 26.A flower bud , showing aestivation from outside to inside:abaxial central lobe , abaxial lateral two and finally adaxial two , indumentum
on the outer surface of corolla.25.×72.26.×24.27.A flower bud , showing aestivation from outside to inside:adaxial two lobes , abaxial
lateral two and finally abaxial central one , ×18.28-31.Early development of two carpel primordia.28.Further sinking of meristem ,×240.29.Sinking area forming a hole;carpels becoming arched in shape;anterior stamens growing horizontally;slit between anther locules
starting differentiation , ×150.30.Two carpels growing upwards , and their margins starting separation , ×240.31.Two carpels growing
quicker on dorsal side than on ventral side , thus both becoming u_shaped , ×180.32-34.Development of androecium and gynoecium.32.
The abaxial carpel rapidly growing and slightly enveloping margins of the adaxial carpel , making the top of carpels unequally 2_lipped;fertile
stamens growing horizontally , anthers sinking longitudinally and anther locules had differentiated;staminode getting lamellar , ×60.33.An-
ther locules longitudinally elongating;conical and unequally 2_lipped stigma constricted near the top , ×30.34.Developing fertile stamens
and staminode , and verrucose protuberances and indumentum on the outer surface of ovary , ×18.
Abbreviations:Al , anther locule;C1 , abaxial carpel;C2 , adaxial carpel;Cb , abaxial lateral lobe primordium of corolla or abaxial lateral
lobe of corolla;Cc , abaxial central lobe primordium of corolla or abaxial central lobe of corolla;Co , connective;Sn , staminode primordium or
staminode.
PAN Kai_Yu et al:Floral Organogenesis of Titanotrichum oldhamii(Gesneriaceae) 899　
Figs.35-44.　35-39.SEM photographs of floral organs.35.A flower bud with sepals removed to show adaxial corolla lobes , one abaxial
lateral lobe , fertile stamens , style and stigma , ×12.36.Fertile stamens , showing subulate filaments , ×15.37.Fertile stamens , showing
dorsifixed anthers , ×12.38.Gynoecium , showing ovary , style and stigma , ×12.39.Enlargement of stigma shown in Fig.38 , ×48.40 ,
41.Transverse and longitudinal sections of ovary , showing two parietal placentae.40.×12.41.×21.42-44.Transverse sections of ovary
5 mm long and embedded in wax , showing one locule and two parietal placentae from near the base to near the top.42.Near the top , ×128.
43.At the middle , ×64.5.44.Near the base , ×51.
Abbreviations:Fi , filament;O , ovary;ST , style;St1 , abaxial stigma;St2 , adaxial stigma.
of two carpels had fused to form a syncarpous ovary , pro-
truded inwards and reflexed , so that they did not fuse at
the centre and thus formed a one_locular ovary(Fig.40).
In the longitudinal section the placentae with numerous
ovules extended from the base to the top of ovary without
formation of central septum(Fig.41).Consecutive trans-
verse sections of a flower 5 mm long and embedded in wax
show that margins of the two carpels completely fused and
protruded inwards to nearly the centre but reflexed , and
thus they did not fused there.Therefore , two_carpellary
ovary still maintained one_locular , with two parietal pla-
centae (Figs.42-44).
3　Discussion and Conclusion
3.1　The structure of stigma
Wang et al[ 1] and Li and Kao[ 3] considered that the
genus Titanotrichum had two_fid stigma with the anterior
segment lingulate and shallowly two_lobed.Our investiga-
tion shows that the two carpels maintain free at the apex
from initiation (Figs.33 , 34).Their apices are always
free and have never fused at all the stages of develop-
ment.We also found that the carpels constrict only near
the top and their apices become unequally two_lipped.As
intercalary growth takes place in the constricted region the
900　 植物学报　Acta Botanica Sinica　Vol.44　No.8　2002
style differentiates and elongates , and the stigma contin-
ues to differentiate till its maturity , but no further division
is found for the lower segment (Figs.35 , 38 , 39).This
pattern of development is consistent with that of Rehman-
nia glutinosa revealed by WANG Yin_Zheng and his co_
workers(WANG Yin_Zheng s unpublished data).
3.2　Anthers always free
Wang et al
[ 1]
and Li and Kao
[ 3]
consider that an-
thers of the four fertile stamens connate at the top in pair ,
but the present study shows that the anthers are always
free from their initiation to maturity.
3.3　The initiation and development of primordia of
calyx , corolla and androecium
It was found in the present investigation that in the
genus Titanotrichum sepals are free and all derived sepa-
rately from different sepal primordia , which are connected
to each other laterally only at the very base , and thus they
are connate only at the very base(Fig.14).According to
initiation and size of the sepal primordia , the initiation
order of sepal primordia is from abaxial two sepal primor-
dia , adaxial one and finally to adaxial two (Figs.7-9),
while their development order is from adaxial sepal , later-
al two and finally to abaxial two (Figs.10-14).Accord-
ing to the present observations , initiation and development
of corolla lobe primordia are consistent in order , i.e.first
abaxial central lobe , abaxial lateral two and finally adaxi-
al two (Figs.16-24).Aestivation of corolla is found to
be imbricate:from outside to inside abaxial central lobe ,
abaxial lateral two , and finally adaxial two (Figs.25 ,
26), or abaxial lateral two lobes , adaxial two and finally
abaxial central lobe (Fig.27).The posterior stamen pri-
mordia are earlier than the anterior ones in initiation , but
they are simultaneous in development;the staminode pri-
mordium is simultaneous with the posterior stamen primor-
dia in initiation , but smaller and delayed in development.
Finally , the staminode is without differentiation of anther
and filament , and is lamellar in structure , only 0.75 mm
long (Figs.19-23).
3.4　Comparison with related groups
Most authors
[ 3 , 9 ,12]
emphasize number of ovary
locules in delimitation between the Scrophulariaceae (two_
locular , with axile placentation) and the Gesneriaceae(one_locular , with parietal placentation).The Gesneri-
aceae is usually one_locular , with parietal placentation ,
less frequently two_locular , with axile placentation , or
two_locular but one locule developed while the other re-
duced.The observations on floral organogenesis show that
in Rehmannia of the Scrophulariaceae and Rhynchoglos-
sum of the Gesneriaceae ovary changes in number of
locules with development from two_locular with axile pla-
centation in the lower part to one_locular with parietal pla-
centation in the upper part[ 13](WANG Yin_Zheng s un-
published data).In Whytockia of the Gesneriaceae the
ovary is always two_locular with axile placentation from
the base to the top
[ 14 ,15](WANG Yin_Zheng s unpub-
lished data).The initiation of carpel primordia in Titan-
otrichum is consistent with that in Whytockia , Rhyn-
choglossum and Rehmannia.In the genus under study ,
however , margins of two carpels primordia curve inwards
and fuse , forming a syncarpous ovary , and the margins
continue to extend toward the centre , but they do not fuse
there , and thus the ovary maintains one_locular , with two
parietal placentae (Figs.28-34), and is different from
those in the above three genera.The order of development
of sepal primordia in Titanotrichum is from adaxial sepal
to abaxial , and is almost completely consistent with that
in Rehmannia and Whytockia , but different from that in
Rhynchoglossum , which is simultaneous in development.
The aestivation of sepals in Titanotrichum is valvate and
is similar to that in Rhychoglossum and Rehmannia , but
different to that in Whytockia which is imbricate[ 13](WANG Yin_Zheng s unpublished data).
The order of initiation of corolla lobe primordia in
Titanotrichum (abaxial central lobe , abaxial lateral two ,
and adaxial two) is basically similar only to that in
Rehmannia (WANG Yin_Zheng s unpublished data),
and different from that in Whytockia and Rhynchoglos-
sum , where all the five primordia initiate simultaneous-
ly[ 13](WANG Yin_Zheng s unpublished data).At the
stage of flower bud the aestivation of corolla lobes in Ti-
tanotrichum (Figs.25-27)differs apparently from that in
Rehmannia and Whytockia:abaxial two lobes , adaxial
two and abaxial central one from outside to inside(WANG
Yin_Zheng s unpublished data);no observation has been
conducted for Rhynchoglossum .
The four genera are different from each other in order
of initiation of fertile stamen primordia.In Whytockia and
Rhynchoglossum , they arise simultaneously[ 13] (WANG
Yin_Zheng s unpublished data), in Rehmannia the ante-
rior promordia occur first (WANG Yin_Zheng s unpub-
lished data), while in Titanotrichum the posterior ones
come first(Figs.16 ,17).With initiation stamen primor-
dia are earlier than corolla lobe primordia in Whytockia(WANG Yin_Zheng s unpublished data), but later than
those in all the other three genera , which are consistent in
this respect.
We understand , based on the observations on floral
organogenesis of the above four genera , that floral organo-
genesis is diverse in the Scrophulariaceae and Gesneri-
aceae.Relationships between the two families in floral
organogenesis are also complex;the four genera do not
form two patterns:one in the Gesneriaceae , while the
other in the Scrophulariaceae.The delimitation between
the two families as conventionally done using number of o-
vary locules and placentation type is not convincing.The
two families need to be further studied in systematics.
Acknowledgements:The authors are grateful to Prof.
HONG De_Yuan for the improvement of English language ,
Mr.XIAO Yin_Hou for his help in SEM observation , Mr.
YANG Xue_Jian for developing photos , and Miss WEN
Jie for preparation of wax_sections.
References:
[ 1] 　Wang W_T(王文采), Pan K_Y(潘开玉 ), Li Z_Y(李
振宇).Gesneriaceae.Wang W_T (王文采).Flora
PAN Kai_Yu et al:Floral Organogenesis of Titanotrichum oldhamii(Gesneriaceae) 901　
Republicae Popularis Sinicae.Tomus 69.Beijing:Science
Press , 1990.578-581.(in Chinese)
[ 2 ] 　Zhen C_Z(郑朝宗).Flora of Zhejiang.Vol.6.Hangzhou:
Zhejiang Science and Technology Publishing House , 1993.
61.(in Chinese)[ 3 ] 　Li Z_Y(李振宇), Kao M_T(高木村).Gesneriaceae.
Huang T_C(黄增泉).Flora of Taiwan.Vol.4.Taipei:
Editorial Committee of the Flora of Taiwan , 1998.708-
710.
[ 4] 　Forbes F B , Hemsley W B.Enumeration of all the plants
known from China Proper , Formosa , Hainan , the Corea ,
the Luchu Archipelago and the Island of Hongkong , together
with their distribution and synonymy.J Linn Soc Bot ,
1890 , 26:194.[ 5 ] 　Solereder H.Uber die Gattung Rehmannia.Ber Deutsch
Bot Gesellsch , 1909 , 27:390-404.
[ 6 ] 　Sealy J R.Titanotrichum oldhamii.Curtiss Bot Mag ,
1949 , (166):tab.78.[ 7 ] 　Burtt B L.Studies in the Gesneriaceae of the Old World ⅩⅩⅣ.Tentative keys to the tribes and genera.Notes Roy
Bot Gard Edinb , 1962 , 24:204-220.[ 8 ] 　Kvist L P , Pedersen J A.Distribution and taxonomic impli-
cations of some phenolics in the family Gesneriaceae deter-
mined by EPR spectroscopy.Biochem Syst Ecol , 1986 , 14:
385-405.[ 9 ] 　Wang W_T(王文采), Pan K_Y(潘开玉), Li Z_Y(李振
宇).Key to the Gesneriaceae of China.Edinb J Bot ,
1992 , 49:5-74.
[ 10] 　Smith J F , Wolfram J C , Brown K D , Carroll C L , Denton
D S.Tribal relationships in the Gesneriaceae:evidence
from DNA sequences of the chloroplast gene ndhF.Ann
Mis Bot Gard , 1997 , 84:50-66.[ 11] 　Smith J F , Brown K D, Carroll C L , Denton D S.Familial
placement of Cyrtandromoea , Titanotrichum and Sanango ,
three problematic genera of the Lamiales.Taxon , 1997 ,
46:65-74.[ 12] 　Chin T_L(金存礼).Rehmannia (Scrophulariaceae).
Tsoong P_C (钟补求), Yang H_P(杨汉碧).Flora Re-
publicae Popularis Sinicae.Tomus 67.Beijing:Science
Press , 1979.1.(in Chinese)[ 13] 　Wang Y_Z(王印政), Gao Z_M(高致明), Liang H_X(梁
汉兴), Wu Z_Y(吴征镒).Floral morphogenesis of Rhyn-
choglossum omeniense (Gesneriaceae) and its phylogenetic
implication.Acta Bot Yunnan (云南植物研究), 1997 ,
19:265-270.(in Chinese with English abstract)[ 14] 　Wang Y_Z(王印政), Pan K_Y(潘开玉), Li Z_Y(李振
宇), Hong D_Y(洪德元).An anamorphosis of gynoecium
in Whytockia (Gesneriaceae)with phylogenetic implication.
Acta Bot Yunnan (云南植物研究), 1996 , 18:431-423.(in Chinese with English abstract)[ 15] 　Wang Y_Z(王印政), Pan K_Y(潘开玉).Comparative
floral anatomy of Whytockia (Gesneriaceae) endemic to
China.Zhang A_L(张敖罗), Wu S_G(武素功).Floris-
tic Characteristics and Diversity of East Asian Plants.Bei-
jing:China Higher Education Press , 1998.352-366.
台闽苣苔(苦苣苔科)花部器官的形态发生
潘开玉　李振宇＊　王印政
(中国科学院植物研究所系统与进化植物学重点实验室 , 北京 100093)
摘要:　在扫描电镜下对台闽苣苔(T.oldhamii(Hemsl.)Solereder)进行了花部器官形态发生的观察 ,为探索该类群
的个体发育 、类群间的系统发育关系和进化趋势提供依据。研究发现该属植物萼片 、花冠和雄蕊发生式样均为五
数花类型 ,它们各自来源于花原基上分化出来的萼片原基 、花冠原基和雄蕊原基;花冠与雄蕊的两侧对称性与花冠
上唇生长稍快和退化雄蕊原基发育迟滞相关;萼片原基的发生和发育的顺序是不一致的:萼片原基发生的式样为
近轴中原基—远轴2 原基—2侧原基 ,发育式样则为近轴中萼片—2 侧萼片—远轴 2 萼片 , 花蕾时为镊合状排列。
花冠裂片原基的发生和发育式样是一致的 ,即远轴中裂原基(下唇中裂片)—远轴 2 侧裂原基(下唇 2 侧裂片)—近
轴 2裂原基(上唇 2裂片)。花蕾期卷迭式为覆瓦状排列 ,从外向内:下唇中裂片—下唇 2 侧裂片—上唇 2裂片或下
唇 2侧裂片—上唇 2 裂片—下唇中裂片。雄蕊原基与花冠裂片原基互生 , 前方雄蕊原基在发生上稍迟于后方雄蕊
原基 ,后者与退化雄蕊原基几乎同时发生 , 但较小 ,并与近轴心皮(或柱头上唇)对生。 将该属与玄参科(Scrophulari-
aceae)的地黄属(Rehmannia)、苦苣苔科(Gesneriaceae)的异叶苣苔属(Whytockia)和尖舌苣苔属(Rhynchoglossum)的花
部器官比较发现 ,这四个属在这方面呈现出多样性和交叉。过去一直按子房室数和胎座类型划分玄参科(子房 2
室 、中轴胎座)和苦苣苔科(子房 1 室 、侧膜胎座)这一做法受到了质疑。
关键词:　苦苣苔科;台闽苣苔属;花器官发生
中图分类号:Q949　　　文献标识码:A　　　文章编号:0577-7496(2002)08-0895-08
收稿日期:2002-03-26　接收日期:2002-07-08
基金项目:国家重点基础研究发展规划项目(G2000046801);国家自然科学基金(39870056)。
＊通讯作者。
(责任编辑:王　葳)
902　 植物学报　Acta Botanica Sinica　Vol.44　No.8　2002