400 



NATURAL JUST DRY OF FLANT8. 



Choisya has larger flowers than Gel/era, very analogous to those 

 of Boronia and Diosma, from which they cannot be nicely dis- 

 tinguished so long as the seeds are unknown. The five petals are 

 contorted ; the androceum is diplostemonous, and the five inde- 

 pendent ovaries biovulate ; while the leaves are opposite and trifo- 



Peltostigma pleleo idea. 



Fig. 443. 

 Flower. 



Fig. 444. 

 Longitudinal section of flower (f ). 



liolate, and the flowers disposed in biparous cymes. Medicosma 

 (figs. 439-442) has also opposite leaves, but simple and tolerably 

 large tetramerous flowers, with contorted or imbricated petals. The 

 androceum is diplostemonous, and the carpels independent in the 

 ovary. Platydesma may perhaps be defined : a Medicosma, with 

 ovaries not completely independent of each other, and each including 

 from four to six biseriate ovules. Didcrillyea, a New Caledonian 

 plant, has the same tetramerous flowers as the two preceding genera, 

 with a single four-celled ovary, an isostemonous androceum, and 

 opposite trifoliolate exstipulate leaves. 1 



with these leaves are indicated, represented by 

 anthers " sessile cuneiform, united at the base 

 with extrorse dehiscence," two-celled. In the 

 female flowers there are two independent carpels 

 described as superposed to the sepals ; each is 

 formed of a one-celled ovary, surmounted by a 

 short style immediately dilated into a large head, 

 like a crest rolled up, quite covered with a stig- 

 matic papilla, and traversed by a middle groove 

 descending by the internal edges of the ovary. 

 Corresponding to this border is a placenta, sup- 

 porting a descending ovule with exterior and 

 superior tnicropyle prolonged into a sinuous tube, 

 dilated at the apex. The fruit is described as 

 formed of one or two drupes with a bony stone. 



The descendent monospermous seed contains a 

 largo fleshy embryo, with plano-convex coty- 

 ledons and short radicle. By these characters 

 the plant would seem as though it might be 

 considered as a reduced type of Zantlioxylon. 

 The only species known is D. exeelsa (_D. tnada- 

 yascariensisW .). — Anthcea exeelsa Nor. & Dtrp.- 

 Th., loc. cit. — Didymomeles madagascariensis 

 Sprf/ng. 



1 The two genera Astropliyllum and Peltos- 

 tigma (figs. 443, 444) are doubtfully placed here. 

 The former because the only flower which we 

 ha' r e been able to study did not belong with cer- 

 tainty to the specimen accompanying it ; it may 

 be thus defined: — A Zantlioxylon with squami- 



