兰花蕉的胚胎学研究

兰花蕉（Orchidantha chinensis T.L.Wu）的胚珠倒生，具厚珠心和双珠被。内外珠被形成珠孔。假种皮从外珠被的项端发生。造孢时期，胚珠具有一层周缘细胞。造孢细胞发育成大孢子母细胞，大孢子母细胞减数分裂形成大孢子的线形四分体，少数三分体。合点大孢子具功能。胚囊发育属蓼型。成熟胚囊的合点端狭长，胚珠具有珠心冠原和承珠盘。反足细胞寿命长，胚珠维管束属于合点后多维管束类型。胚乳发育属核型。种子脱落时，胚尚未分化出胚芽和胚根。

EMBRYOLOGICAL STUDY ON ORCHIDANTHA CHINENSIS (LOWIACEAE)

Embryologicalfeaturesof threatenedOrchidantha chinensis werestudiedwiththehelpof a Leitzmicroscope.LivingspecimenswerecollectedfromtheSouthChinaBotanicGardenat Guangzhou.Specialemphasisis givento the ovuledevelopment,megasporogenesis,megagametogenesisand the developmentof endosperm.Theovulesof O.chi nensis areanatropous,crassinucellateandbitegmic.Micropyleis formedby innerandouterinteguments.Ariloriginatesfromtopendof outerintegument.Theovulehasa layerof parietalcellsatthesporogenousstage.Sporogenouscelldevelopsintoa megaspore mothercell,andthendividesmeioticallyintoa linearmegasporetetrad,andsometimestriad.Chalazal megasporeis functional.The developmentof theembryosac is of Polygonumtype.Chalazalendof matureembryosacis narrowandelongated.Theovulehasepistaseandhypostasestructures.Antipodal cellsarelongevous.Thetypeof vascularbundlein theovulebelongsto postchalazalmultibundles.The developmentof endospermis of nucleartype.Plumuleandradiclearenotdifferentiatedwhentheseeds fall.We recognizethatthe elongatedpartof the ovary in Lowiaceaeis functionalfor continuous developmentof pollen.Maincharacteristicdifferencesamong8familiesin Zingiberales,and the reproductivebiologyof Lowiaceaearediscussed.