APOCYNACEAE. 
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 GENERA. 
Discus wantin 
ng. 
ndocarp winged, drupe always 1-celled, large, bright r PHU) Sala Pter a 
Endocarp compeapesd: deeply furrowed underneath, drupe 2-celled, ava poerces 
osia 
Diseus pre ne at We lg howe ee SR pe SES © ET RL SORE Tae ee ey Le Rh ee 
eaves whorled, drupe smooth, small, black, obcordate. v5... vs eese 2. Rauwolfia 
PTERALYXIA K. Sch. 
Calyx deeply 2-parted, with almost free, imbricate lobes, glandless. Paks tubular, 
without scales at the constricted throat, and short obtuse sinistrorse lo Stamens in- 
serted below im throat, ovate-lanceolate, acute. Discus absent. Oris: superior, with 
: pendulous ovules in ea ach cell. Style filiform, with aaa era thickened stigma, which 
is shortly 2-lobed. Drupe dry, obovate, bright red. with 2 large oa 
eae oe and 2 sharp midale- erests. Seeds large (3 jo 3. 5 em long, and 1 to 1.5 ¢ 
n diam.), with ruminate album 
A Hawaiinn genus with a single arborescent species, peculiar to the Island 
of Oahu. The species was first deseribed by Hillebrand in the genus Vallesia 
as V. macrocarpa Hbd. According to K. Schumann the plant is nearest related 
to the genus Alyxia. 
bo 
Pteralyxia macrocarpa (Hbd.) K.. Sch. 
Kaulu. 
YXIA nisi al Hbd.) K. Schum. in Engl. et Prantl Pfizfam. IV. 
seeks 151.—Va ie Hbd. Fl. Haw. TL " (1888) 297;— Del Cast. tL 
lles: 
. Mar. Pacif. “VIL. eee 232. 
sng very tenacious milky sap; 
the apex, coriace- 
owered, 
agit ealyx 2 mm, lobes obtuse short; corolla pale ear — 
stamens with ver egi se ar: anthers — style nearly thé 
drupe ttt Eola m7 2h age e wide, bright red; seed elliptical, 36 mm long, 16 
im broad and - mm Pen poten ee both ends; — deeply wrinkled by chant 
sinuous folds; embryo axile, straight, nearly as long a 6 nea 
ony cotyledons uve as long as the inferior radicle co seareely broader. 
407 
