RUBIACEyE 877 



Distribution. Low wet sandy swamps on the borders of streams; coast region of South 

 Carolina through southern Georgia and northern Florida to the valley of the lower Apala- 

 chicola River; rare and local. 



2. EXOSTEMA Rich. 



Trees or shrubs, with terete branchlets, and bitter bark. Leaves sessile or petiolate, 

 persistent; stipules interpetiolar, deciduous. Flowers axillary and solitary or in terminal 

 pedunculate cymes, fragrant, the peduncle bibracteolate above the middle; calyx-tube 

 ovoid, clavate or turbinate, the limb short, 5-lobed, the lobes nearly triangular, persistent; 

 corolla 5-lobed, white, salver-form, the tube long and narrow, erect, the lobes of the limb 

 linear, elongated, spreading, imbricated in the bud; filaments filiform, exserted, united at 

 base into a tube inserted on and adnate to the tube of the corolla; anthers oblong-linear; 

 ovary 2-celled; style elongated, slender, exserted; stigma capitate, simple or minutely 2- 

 lobed ; ovules numerous, attached on the 2 sides of a fleshy oblong peltate placenta fixed 

 to the inner face of the cell, ascending. Fruit a many-seeded 2-celled capsule septicidally 

 2-valved, the valves 2-parted, their outer layer membranaceous, separable from the crusta- 

 ceous inner layer. Seeds compressed, oblong, imbricated downward on the placenta; 

 seed-coat chestnut -brown, lustrous, produced into a narrow wing; embryo minute, in fleshy 

 albumen; cotyledons flat; radicle terete, inferior. 



Exostema with about twenty species is confined to the tropics of America, and is most 

 abundant in the Antilles, one species reaching the shores of southern Florida. The bark 

 contains active tonic properties, and has been used as a febrifuge. 



The generic name, from ew and ar^ua, relates to the long exserted stamens. 



1 . Exostema caribaeum R. & S. Prince Wood. 



Leaves oblong-ovate to lanceolate, contracted into a slender point and apiculate at apex,. 

 gradually narrowed and cuneate at base, entire, thick and coriaceous, dark green on the 

 upper surface and yellow-green on the lower surface, l'-3' long and %'-\\' wide, with a 

 prominent orange-colored midrib and conspicuous reticulate veinlets; unfolding in the 

 autumn and in early spring and summer, and persistent for 1 or 2 years; petioles slender,. 



Fig. 772 



orange-colored, %'-%' in length; stipules nearly triangular, apiculate, with entire dentate or 

 ciliate margins, about T V long, and in falling marking the branchlets with ring-like scars. 

 Flowers axillary, solitary, appearing from March until June, about 3' long, on slender pedi- 

 cels spirally twisted before the flowers open; calyx-tube ovoid; corolla glabrous; filaments 

 united into a short tube. Fruit f ' long, becoming black in drying; seeds oblong, f ' long, 

 with a dark brown papillose coat and a light brown wing. 



