THE STUDY OF THE EVOLUTION OF THE FLOWER. 289 



Vascular Structure. 



Serial sections througli very young flowers and hand-sections of sterile "fruits" were 

 prepared from only one species — N. sylvatica. 



In one flower six bundles were present la the lower portion of the ovary (Text-fig. 12, 

 A), these extended upward toward four petals, j?^, and two stamens, st (B-E) ; in another, 

 nine bundles occurred (H), but only seven of these supplied stamens (three) and petals (I). 



An inner series of fine branches originates from the cylinder of bundles near the 

 point of attachment of the ovules (D, E) and extends into the style (E). The branch d 

 occupies a dorsal position in the style, but the flowers were too young to show the 

 vascular connections of the ovule, hence the nature of tiie remaining branches could not 

 be determined. Erom sections of fruits it appears that two or three strands unite to 



form the ovular bundle (J). 



Owing to the variability in the flower in the genus, a comparison needs to be made 

 with the remaining species before the significance of the vascular peculiarities can be 



adequately discussed. 



Comparisons. 



Endlicher* placed Nyssa in a nevv family, the Nyssacese, near the Santalaceai. 

 Baillont transferred it to the Combretacese for reasons similar to those which influenced 

 him in attaching Alangimn to this family. But the occasional presence of two styles, 

 one of which is rudimentary in N. sylmtica, and the recorded case of a second incomplete 

 loculus indicate that the ovary is unilocular by abortion. Bentham & Hooker % and 

 Harms § include iVy 55a among the^Cornaceae, but it differs from Cormis in possessing the 

 Aralian type of ovule, in its variable flowers, imbricate corolla, free styles, and reduced 

 ovary. Wangerin \ separates it from the Cornaceae on the ground that the ovule is 

 bitegumentary, but since the ovule possesses only one integument this criterion fails. 



Nysm approaches Aralia in the form of ovule (adaxial). But the ovules of Aralia 

 are parietally borne, whereas the ovular bundles of J^yssa, by analogy with Griselima, 

 might indicate that the ovule was originally axially suspended. A closer structural 

 agreement exists between I^ysm and Davidia, both genera possessing polygamous 

 flowers, free styles, and numerous stamens. 



SUMMAUT, 



1. The following details of floral morphology are recorded ; 



a. The occasional occurrence of hermaphrodite flowers in Aucuha Umalaka. 

 h. Biovulate ovaries in A.japonica and himalaica. ^ 



o. Anomalous flowers in the hybrid Garrya Thuretii-ih^s^ consist of three 



congenitally united flower-heads borne upon one " pedicel," thus combmmg 



S. Endlicher, Gen. PL 328. t H. B.illoa. Bull. Soc. I^^-'J-^'';- <1^,^!> ^^ ^ ^^.. 



% Bentham et kooker. Gen. PI. i. 952. § Har,ns in Engl. u. Prantl, Nat. Pfl. Ted uu Abt. 8. 2o7. 



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