APOCYNACrLAE. 



The family Apocynaceae consists of about 1000 species, the larger number 

 of which belong to the tropics. Of its 133 genera only five are represented in 

 the Hawaiian Islands, three of which have arborescent species. One genus 

 (Pteralyxia K. Sch.) is endemic, with a single species. The largest number of 

 Apocynaceae are climbing shrubs, while erect shrubs or trees are not as nu- 

 merous. In these Islands we have only one climbing plant of this family, the 

 well-known Maile of the natives, Alyxia olivaeformis Gaud., while the re- 

 maining ones are trees, with the exception of the cultivated Vinca rosea, which 

 has also become naturalized, having escaped from cultivation. Annuals are not 

 known in this family. Of interest and usefulness is the milky sap which nearly 

 all members of this family possess, as it contains caoutchouc. Not a few of the 

 species of Apocynaceae are extremely poisonous, and undoubtedly these strong 

 poisonous substances are to be found in the milky sap. 



KEY TO THE GENEEA. 



Discus wanting. 



Endocarp winged, drupe always 1-celled, large, bright red 1. Pteralyxia 



Endocarp compressed, deeply furrowed underneath, drupe 2-celled, large, yellow. 

 3. Ochrosia 



Discus present. 



Leaves whorled, drupe smooth, small, black, obcordate 2. Rauwolfia 



PTERALYXIA K. Sch. 



Calyx deeply 2-parted, with almost free, imbricate lobes, glandless. Corolla tubular, 

 without scales at the constricted throat, and short obtuse sinistrorse lobes. Stamens in- 

 serted below the throat, ovate-lanceolate, acute. Discus absent. Ovary superior, with 

 2 pendulous ovules in each cell. Style filiform, with subglobose, thickened stigma, which 

 is shortly 2-lobed. Drupe dry, obovate, bright red. Putamen with 2 large winged 

 lateral angles and 2 sharp middle-crests. Seeds large (3 to 3.5 cm long, and 1 to 1.5 cm 

 in diam.), with ruminate albumen. 



A Hawaiian genus with a single arborescent species, peculiar to the Island 

 of Oahu. The species was first described by Hillebrand in the genus Vallesia 

 as T 7 . macrocarpa Hbd. According to K. Schumann the plant is nearest related 

 to the genus Alyxia. 



Pteralyxia macrocarpa (Hbd.) K. Sch. 

 Kaulu. 



PTEBALYXIA MACKOCARPA (Hbd.) K. Schum. in Engl. et Prantl Pflzfam. IV. 2. 

 (1895) 151. Vallesia macrocarpa Hbd. Fl. Haw. Isl. (1888) 297; Del Cast. 111. 

 Fl. Ins. Mar. Pacif. VII. (1892) 232. 



A small tree with short and thick diverging branches and very tenacious milky sap; 

 leaves obovate or obovate-oblong, on petioles of about 5 cm; rounded at the apex, coriace- 

 ous, pale, glabrous, veins prominent, strictly parallel; cymes contracted, 6 to 12 flowered, 

 terminal, sessile on short leafy spurs or branches, pedicels very short, with squamaceous 

 bractlets; calyx 2 mm, lobes obtuse short; corolla pale yellow, tube 6 to 8 mm, lobes 2 to 3 

 mm; stamens with very short filaments, anthers acute; style nearly the length of the tube; 

 drupes dry, 5 cm long. 2.5 cm or more wide, bright red; seed elliptical, 36 mm long, 16 

 mm broad and 12 mm deep, pointed at both ends; albumen deeply wrinkled by transverse 

 sinuous folds; embryo axile, straight, nearly as long as the albumen, the linear oblong 

 fleshy cotyledons about as long as the inferior radicle and scarcely broader. 



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