24 KEY TO THE GENERA OF MANHATTAN PLANTS. 



173. Circaea. Fruit indehiscent, beset with hooked hairs (2-celled, 2- 

 seeded, rounded, tapering below into the pedicel). 



Order 66. HALORRHAGLDACEAE. 



174. Myriophyllum. Fruit 4-celled, 4-lobed, 4-seeded, indehiscent sessile 

 in the axils of the leaves. Aquatic herbs. 



Order 67. UMliELLIFERAE. 

 Fruit 2 carpelled, dry. At maturity the 2 carpels separate from 

 the central axis, forming 1-seeded, indehiscent akene-like bodies. Calyx 

 superior. The back of each carpel is provided with 5 primary ribs or 

 wings, and often with 4 intermediate or secondary ribs. Fruit in umbels 

 or heads. 



175. Polytaenia. Carpels much flattened dorsally, oval, 3 ribs on back 

 fine, 2 lateral corky- thickened. 



176. Peucedanum. As above, but lateral ribs thin-winged. 



177. Sanicula. Carpels nearly globose, beset with hooked prickles. 



178. Osrnovrhiza. Carpels linear, attenuate downward into a tail, some- 

 what bristly (2-3 cm long). 



179. Cicuta. Carpels slightly compressed laterally, ribbed (3-4 mm). 



180. Deringa. Carpels linear, glabrous, ribbed (5-7 mm). Umbels 

 irregular. 



181. Spermolepis. Carpels small (1$ mm), ovate, papillose, ribbed. 



Order 68. CORNACEAE. 



182. Cornus. Drupe with a 2-celled, 2-seeded stone. Calyx superior. 

 (In cymes, blue or white. Stone longitudinally ridged. Shrubs.) 



Order 69. PRIMULACEAE. 

 Capsule 1-celled, placenta central, seeds several. Herbs. 



183. Androsace. Capsule 5-valved at apex (ovoid, 4 mm.) 



184. Steironema. Capsule 4-valved at apex (globose, 5-6 mm). 



185. Anagallis. Capsule dehiscent by a circumcissile line about the 

 middle. 



Order 70. OLEACEAE. 



186. Fraxinus. Samara sy metrically winged from apex. Trees. 

 (Calyx inferior, minute, persistent. Wing somewhat decurrent along 

 the sides. Samara 1-celled, 1-seeded.) 



Order 71. GENT1ANACEAE. 



187. Gentiana. "Capsula oblong, 2-valved, 1-celled, dehiscent through 

 the 2 ventral sutures. Seeds very numerous, borne over the whole inner 

 surface of the capsule." 



Order 72. APOCYNACEAE. 



188. Apocynum. Fruit 2 long and slender follicles. Seed numerous, 

 provided with a coma at apex. (Follices pendent, glabrous, 10 cm.) 

 Herbs, 



