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The embryo1ogy of Buddieja da ,zd11Franch

Yoshiaki HAYASHI and SuekoSAT0*

Department of Science Edし1cat1on,Faculty of Educ1t1on,Fukushima Unlver?Itv,960-12,Japan(Recieved 10September.1981)

Not .?o many observat1ons on the embryology of f-111(i?ii(・la.a gent_Is of the I ogan1ace le (s.1),

have been made,1.e,Dop (1913)ir1 B - ,1ifo11?l and Soueges (1940)In B 1,- abili?;、.Dop (1913) reported that the endosperm development is the cellular type,that i tapetal layer of integument encloses the embryo、lao and that endosperm h1ustona are fom ed.Soueges (1940)described that early development of the proembryo isof theOnagrad type.These observat1ons may be summarized as the development of the embryo sac conforms to the Polygonum type,the endosperm Is cel ular and the embryogeny conforms to theOnagrad type.According to Davis (1966),there has been no observation on the development and structure of the anther or that of the pollen grains.

The present Investigation was undertaken to study the embryology of fiuddif7a da1,1dii F anch

Material and Methods

?'.Ii?- 1f11nat1ve to China ls often c1_titivated a ga-den domestically as on amentai,notably specie、、of the b1_1tterfly bush,in Japan.

Fief,al buds at different stages of development of B ?i?- d11were collected from a plant culti-

vated in a private gal-den In Sendai City,and fixed In formalin-acetlc.alcohol and Navaschin's f1しlid.Of these the forn er fixative gave better rcsults.Customary methods of dehydration, embedding and sect.1on1ng were followed (Johansen,l940).The sections were stained mostly with Iron_alum haematoxylin and safranln.Smear preparations of pollen were also studied.

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The pollen gralr1s are shed at the two.nuciel stage,and are of the tr1colpate type with thlee germ pores.

Meg(Is?01,og?n ,sis. The megaspore mother cell is seen first as a large sub_epidermal cell of the nuce11us.The nucellus is of the reduced type (tenulnucellus).The mature ovule is,hemi- anatropous and consists of a single integument which at this stage has not enclosed the nucelh_Is by the end of July(Fig.4-1).Meanwhile the integumer,t has Increased in length and by the time meiosis is completed It encloses the nuce11us latera11y.The single layer of lntegument cells adjacent to the chalazal two-thirds of the en bryo sac 1s u petし1m_like In appearance.These cells are cubical or columna in shape and the protoplastsare denser than those of the other Integument cell (Fig.4-2).Anlntegunent tapetum ls differentiated and a hypostasels formed directly below the embryosac.The primary archesporial cell does not cutoff a cover cell but functions directly as the megaspore motherce11.Thelatterforms four linearly a ra nged megaspores by the beginning In A gust (Fig.2-1).The most chalazal end of which usually develops into the emaryosac.

Fm a1? game1oPfiyt?. The functioning megaspore increases its volume and then the nucleus divides three times and u通mately an eight-nucleate embryo sac ls formed (Figs.2_2,2_3,2_4) As the macrogametophyte approaches to the stage of maturity?the two polar nuclei migrate from opposite ends to the center of the embryo sac and fuse to form a large secondary nucleus with a prominent nucleolus,

At maturity the embryo sac has three antipodal cells,a secondary m.1cleus produced by the fusion of the two polar nuclei before fertilization,and the egg apparatus consisting of an egg cell and two synerglds.In the mature embryo sac the antipodal cells persist Into early endosperm formation,and the synergids are pynform.

From the above description,It may be obvious that the embryo sac development in fj tfd- f加conforms to the Polygonum type'(Maheshwan,1950),which is the most common In occurrence not only in angiosperms as a whole bu'1_ also In such a single family as Loganiaceae (s.1.)

Emby?ogtny. After fertilization,the endosperm nucleus moves toward the chalazal end of the embryo sac.The first division of the endosperm nucleus Is transverse and ls followed by wall formation,thus dividing the embryosac1ntotwochambers,of which the mcropylarls much larger than the chalazal (Fig.4_3).The nuclei of both chambers divide almost simultaneously or rarely successively,each division being followed by wall deposition until the embryo sac cavity becomes filled with a mass of thin_walled cells (Figs.2_5,2-6). Accordingly, the endosperm formation of this species ls of 1_he cellular type.

In this species,the zygote does not divide until many endosperm ceils are formed.The firstdivision of the zygote is transverse,resulting In the formation of a terminal ceil and a basal cell (Fig.2_6).Usl.1a11y a transverse division occurs in the temnal ce11before the basal one divides

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7)The ovules are hemianatropous,tenu1nuce11.1r and unltegmic.8)The prmary archesporial ce1l funct1or1s dlreclv as the megaspore mother cell.9)After undergoing the me1osis of 1.he megaspore mother cell the linear tetr ;1d ls formed.

The three mcropyla1・megaspores of the tetrad degenerate and the chalazal one develops Into In embryo sac of Polygonum type.The3 antipodal cells persist into early endosperm formation

10)Fertilization is porogamo1_ls.The endosperm is cellular.Embryogeny conforms to theOnagrad type.Thlckened integ、し1mentary tapetum Is formed,and a hypostase ls formed.

References

Dahlgren,K,V0 .1922 Die embryo1og1ederLogm azeen_Gattl,1ngSplgi ila.Svensk Bot.Tldskr 16177_87.

Davisf GL.1966 Systematic Embryology of the Angiosperms.New York,London,Sydney.Dop p 1913Recherches sur la deve1oppement et la nutrition du sac embryonnane et do

1endosperme desBtiddiela_Bu11.Soc.Bot.France6019-16,45-50,92-98.Johansen,DA 1940 Plant Microtechn1(tue.McGraw Hill,New York.Johansen。DA 1950 Plant Embryo1ogy.Chf・onica Botanica Co.,Walthan ,Mass.Maheshwan,P i950 An Introduction to the Embryology of Ang1osperms.McGraw Hill, New

York,Toronto and London.Mohrbutter,C.1936Embryologlsche Studlen an Loganiaceer1.Planta 26164-80.Moore,R.J.1948 Cytotaxonomic studies in the Logamaceae I1.Enbryology of Poiyplmlum

f)1,o(amb(n、 L.Amer.J.Bot.35 ;404-410.

Soueges,R.1940 Embryogenic dos Logn iacees.Deve1oppment del'embryon chezleEuddeia m labiiis Hemsley.C.R.Acad.Sci.Paris 211;139_140.