68 ANNONACEAE. 
ASIMINA. Papaw. 
(Family Annonaceae). 
Small trees or arborescent 
shrubs: deciduous. Twigs round- 
ed, moderate. Pith roundish, 
white, continuous with firmer 
greenish diaphragms, or becom- 
ing brownish and chambered in 
age. Terminal bud clearly naked, 
larger, the lateral obliquely super- 
posed with the uppermost globose 
and stalked when a flower-bud or 
oblong and subsessile when a leaf- 
bud. Leaf-scars alternate, 2- 
ranked, half-round becoming 
broadly crescent- or horseshoe- 
shaped by rupture of the mem- 
branous top which at first covers 
the. smaller buds: bundle-traces 5 
or 7, sometimes doubled: stipule- 
sears lacking. 
The “papaw” of the northern 
States and the related custard 
apples, sweet-sops, sour-sops, cherimoyas, etc, of the 
tropics, which belong td the related genus Annona, 
illustrate a type of pith which recurs here and there 
(e. g. in Magnolia and Nyssa), in which cross-bands of firmer 
cells are found at intervals. In the present treatment con- 
tinuous pith of this kind is spoken of as diaphragmed, in 
contrast with the chambered pith of Juglans, etc., where the 
cross-bands remain but the softer parts of the pith have 
disappeared. Asimina is somewhat puzzling in this respect, 
for the firm diaphragms are not always readily seen when a 
young twig is split. 
Twigs and especially buds red-hairy. A. triloba. 
