KEY TO THE GENERA OF MANHATTAN PLANTS. 23 



oblong or club-shaped, pubescent with barbed hairs, breaking away at 

 summit. Seed few or several. Herbs. 



Order 63. CACTACEAE. 



Berry inferior, 1-celled, seeds few or numerous on several parietal 

 placentae. (Fleshy, prickly herbs with scale-like leaves.) 



158. Cactus. Plant globose, covered with spine bearing tubercles. 

 (Berry ovoid, scarlet ; seeds few, black, pitted.) 



159. Opuntin. Plant consisting of joints, (Mat, oval. Berry oblong, 

 pink. Seeds numerous, enclosed in a tough aril.) 



Ouder 64. LYTHRACEAE. 



Capsule thin and membranous, tightly enclosed in the calyx tube. 

 Seeds numerous. Placentae axil. Herbs. 



160. Ammannia. Calyx 4-ribbed. Capsule 2-4 celled, but at maturity 

 the partitions break away more or less, leaving tiie placentae in the axis. 

 Dehiscence an irregular bursting. (Capsules clustered in the axils of the 

 sessile leaves.) 



161. Rotala. Differs from Ammannia in having the capsule minutely 

 and densely striate. 



162. Lythrum. Capsule oblong, 2-celled (dehiscent along partitions at 

 top. Calyx 10-14 ribbed, 5-7 toothed with as mauy short appendages in 

 the sinuses. Almost sessile in loose racemes.) 



Order. 65. ONAGRACEAE. 



Fruit inferior, dry, dehiscent or indehiscent, 1-5 celled. Herbs. 



163. Jussiaea. Capsule oblong (arcuate, tapering at base, 5-celled, 10- 

 ribbed, seeds numerous in 1 row, angled). '"Opening between the ribs." 



164. Ludwigia. Capsule short, many seeded (4-angled, 4-celled, dehisc- 

 ing by a hole in the top or breaking away irregularly. Calyx lobes 4, per- 

 sistent). 



165. Epilobium. Capsule linear, many- seeded, 4-celled, loculicidally 4- 

 valved. Seeds numerous, provided with a tuft of fine, soft hair at one 

 end. 



166. Anagra. Capsule 4-celled, loculicidally 4 valved. Seeds numerous, 

 naked. (Capsule in terminal spikes, 4 sided, ribbed, sessile.) 



167. Oenothera. As above (but capsules cylindrical, axilliary, sessile). 



168. Xylopleumm. As above (but capsules shortly pedicelled, clavate- 

 fusiform, in a loose spike with 4 narrow wings and ribbed between). 



169. Megapterium. As above (but capsules axillary, with 4 broad wings, 

 3 cm wide). 



170. Meriolyx. As above (but capsules axillary, sessile, 4-sided, usually 

 arcuate, linear, canescent). 



171. Oaura. Fruit indehiscent, 1 celled, 4-angled or winged (1-seeded). 

 172 Stenosiphon. Fruit as in Oaura, but 8-ribbed, 2 or 3 of the ribs 



winged, transversely wrinkled, villous. 



