M0N0EC1A POLYANDRIA 527 



.WA acnminstion, longer than the flowera. S*ed rettmUing that of the 

 ■fender snary « 

 Ceding, nearly black. 

 1 Gardens, and cultivated lots: common. Fl. August. Fr. Octo. 



A homely weed, and rather troublesome about our gardens. It is also 

 j*J be a nali Te ; but I am not quite satisfied of the fact. 



ixostjs, L. Stem striate, smoothish, much branched ; leaves 

 3 if Isolate : axils spinoso ; flowers pentandrous, in compound 

 Stl and axillary .pikes. Beck, BoU p. 294. 



Thobxt Amakatcthus. 



al Stem IB inches to 2 or 3 feet high, angular-striate, smootbish, 



Root annu -^ mucn brancne d and bushy. Leaves 1 to 2 inches long, and 



often P u .^ h , t ^ an jnch wi(Je) ovate-lanceolate, rather obtuse, mucronate, entire, 



vd" minutely rough ish-dotted, with glaucous blotches beneath ; petioles about 



6 ' "^ the leave»r with 2 subulate spinose stipules al base 1 fourth to half an 



^hto length- Flowers small, clustered in oblong terete erect terminal and 



^terminal spikes. 



\ib Cultivated lots, near West Chester: not common. Fl. August. Fr. Octo. 



' Thjs 5s undoubtedly an introduced plant ; and a vile nuisance it is, where- 



t prevails. It i* abundant in the unimproved streets and alleys, of Philad- 



7!hia- but is yet rare in Chester County. It was collected near West Chester 



I W by D- Townsbwd, Esq. Six or eight additional species are enumerated in 



the U- States. 



[Coltis. Pentandria Digynia.} 



[Xanthium. Ambrosia. Syngencsia Senenonidea.] 



Order 6. Hexandria. 



[Zizania. Triandria Digyvia] 

 [Molanthium. Veratrom. Uexandria Trigynia.'} 



Order 7. Folyandria. 



424. CERATOPHYLLUM. L. Nutt. Gen. 748. 

 [Gr. Zeros, a horn, and Phyllon,* leaf; the dichotomous leaves resembling horns] 



Staxi* ate Fl. Perianth 8 to 10-parted ; segments subulate, equal. 

 Stamens 16 to 20, very short. Pistillate Fl. Perianth as in the 

 staminate flower. Ovary superior ; stigma filiform, oblique, sessile. 

 Xut l-cclled, 1-seeded, indchiscent. 



Herbaceous, submersed aquatics : leaves verticillate, very narrow, dichotomous- 

 ly divided; flowers axillary, solitary. Nat. Ord. 166. Lindl. Ceratophyllbje. 



1. C, demersum, /,. Leaves deeply and often doubly dichotomous; 

 fruit armed with 3 spines. Bech, Bot. p. 124. 

 Dkmersed CiRATOPHTLLTjir. Vulgo — Horn-wort. 



Plant deep green. Root perennial? Stem 6 to 12 or 18 inches long, filiform, 

 branching, smooth, procumbent, or floating, under water. Leaves in numerous 

 verticils of 6 or 8, half an incH to near an inch long, fistular or cellular near the 

 base, once or twice dichotomous, the segments linear, capillary, finely aculeate- 

 denticulate, and mostly with 2 minute aculeate teeth al apex. Flowers axillary, 

 solitary, sessile, inconspicuous. Fruit oblpng, with a loogish terminal spine, 



