APOCYNACEAE 933 



white or colored, rotate or funnelform ; lobes induplicate-valvate. Androecium 

 of 5 stamens. Filaments adnate to the corolla-tube. Anthers versatile. Pollen- 

 grains 3-angled. Gynoecium compound. Ovary 1-celled, with placentae at the 

 sutures. Style entire, terminal. Stigmas terminal, of 2 blades, sometimes 

 nearly sessile. Ovules few or many. Fruit a capsule, this indehiscent, irregu- 

 larly opening or valvate. Seeds with a smooth or variously roughened testa. 



1. LIMNANTHEMUM J. F. Grael. 



Aquatic herbs, with floating or creeping stems. Leaves often all basal : petioles elon- 

 gated : blades always broad, leathery, or membranous when submerged, with a deep sinus, or 

 peltate. Flowers solitary or clustered at the nodes, their pedicels sometimes accompanied 

 by tubers. Calyx green : lobes 5, rather narrow. Corolla white or yellow, somewhat 

 rotate : lobes 5, surpassing the sepals. Stamens 5 : filaments very short, adnate to the base 

 of the corolla. Ovary 1-celled. Capsules slightly longer than broad, indehiscent, or open- 

 ing irregularly. Seeds with a smooth or tuberculate testa. FLOATING HEART. 



Leaf-blades relatively small : corolla about twice as long as the calyx : capsule slightly longer than the 

 calyx : seeds smooth. 1. L. lacunosum. 



Leaf-blades relatively large : corolla about thrice as long as the calyx : capsule about 



twice as long as the calyx : seeds tuberculate. 2. L. aquaticum. 



1. Limnanthemmn lacunosum (Vent.) Griseb. Leaf-blades ovate to orbicular- 

 ovate, 2-4 cm. long, undulate, sometimes pubescent beneath, deeply cordate : flower-clusters 

 usually accompanied by a cluster of slender tubers : calyx usually glabrous, 3-4 mm. long : 

 lobes linear-oblong or linear-lanceolate : corolla white, 6-9 mm. broad : capsules slightly 

 longer than the calyx : seeds smooth. 



In shallow ponds, Nova Scotia to Ontario, Minnesota, Florida and Louisiana. Spring to fall. 



2. Limnanthemum aquaticum (Walt.) Britton. Leaf-blades suborbicular to reni- 

 form, 5-15 cm. in diameter, undulate or repand, cordate, reticulated and pitted on the lower 

 discolored surface : flower-clusters commonly destitute of tubers : calyx 4-5 mm. long : 

 lobes oblong to lanceolate : corolla white, 12-20 mm. broad : capsules twice as long as the 

 calyx : seeds rough. \_L. trachyspermum A. Gray. ] 



In ponds, Delaware and Maryland to Florida and Texas. Spring and summer. 



Order 6. ASCLEPIADALES. 



Herbs, shrubs or trees, commonly with a milky juice. Leaves alternate or 

 opposite : blades entire. Inflorescence cymose, sometimes umbellate. Calyx of 

 usually 5 partially united sepals. Corolla of usually 5 partially united petals, 

 Androecium of 5 distinct or monadelphous stamens, partially adnate to the co- 

 rolla in ASCLEPIADACEAE and accompanied by a 5-lobed crown. Pollen granu- 

 lar or in waxy masses. Gynoecium of usually 2 carpels sometimes only united 

 at the apex. Stigma terminal. Fruit a pair of follicles, or drupaceous. 



Styles united : stamens distinct : pollen loosely granular. Fam. 1. APOCYNACEAE. 



Styles distinct : stamens usually monadelphous : pollen united into waxy 



masses, or the grains in groups of 4. Fam. 2. ASCLEPIADACEAE. 



FAMILY 1. APOCYNACEAE Lindl. DOGBANE FAMILY. 



Perennial herbs, vines, shrubs or trees, mostly with a milky acrid juice. 

 Leaves alternate or opposite, without stipules : blades simple. Flowers perfect, 

 regular. Calyx of 5 persistent sepals imbricated in the bud. Corolla of 5 par- 

 tially united petals, the lobes convolute in the bud. Androecium of 5 stamens 

 alternating with the corolla-lobes. Filaments partially adnate to the corolla- 

 tube. Anthers 2-celled. Pollen-grains simple. Gynoecium of two distinct car- 

 pels or 2 united carpels. Ovary superior, 1-celled with 2 parietal placentae, or 

 2-celled. Styles united. Stigmas simple. Ovules anatropous or amphitropous. 

 Fruit usually of 2 follicles or drupes. Seed often appendaged. Endosperm 

 fleshy. Embryo with straight cotyledons. 



Anthers unappendaged at the base, not connected with the stigma : corolla-lobes sinistrorsely convolute. 

 Fruit drupaceous : shrubs or trees. 



Corolla salverforrn, relatively small ; lobes equilateral, shorter than the tube. 



1. VALLESIA. 



