Buxus.] EUPHORBIACE^. 331 



obtuse or retuse. Spikes small ; bracts and sepals obtuse ; flowers whitish, 

 very crowded. Stamens much exserted ; anthers didymous. Ovary globose. 

 Capsule g in., ovoid, 3-horned, wrinkled. Seeds black. DISTRIB. Europe from 

 Belgium southwards, N. Africa, N. Asia to Japan, W. Asia to W. Himalaya. 

 Bitter and poisonous ; wood used for engraving upon. 



ORDER LXIX. CERATOPKYL LEJE. 



A submerged, branched, slender, fragile herb ; stems cylindric. Leaves 

 whorled, sessile, exstipulate, 2-chotomously cut into linear-toothed lobes. 

 Flowers solitary, axillary, minute, monoecious, enclosed in a 8-I2-partite 

 persistent involucre with subulate lobes. Perianth 0. MALE. Anthers 

 many, crowded, sessile, oblong, cells linear, sunk in a fleshy 2-cuspidate 

 connective, bursting irregularly. FEMALE. Ovary oblong, 1-celled ; 

 style terminal, subulate, persistent, stigma unilateral papillose ; ovule 1, 

 pendulous from the top of the cell, orthotropous. Fruit coriaceous, in- 

 dehiscent, tubercled winged or spurred at the base. Seed pendulous, testa 

 membranous, hilum thickened, albumen ; cotyledons 2-lid ovoid thick, 

 plumule large many -leaved, radicle very short. DISTRIB. Europe, Asia, 

 Africa, N. America (Arctic). AFFINITIES altogether doubtful. PRO- 

 PERTIES unknown. ETYM. itepas and Qv\\ov, from the horn-like leaf-lobes. 

 1. CERATOPHYL'I.UM, L. HORNWORT. 



1. C. demersum, L. ; leaves remotely serrate. 

 Ponds and ditches, from Forfarshire southwards, and in Ireland ; fl. July- 



Sept. Stems 8 in. -3 ft., densely leafy. Leaves 1 in., segments spreading, 



subulate, dark green, flowers found in shallow water only, very incon- 



spicuous. Fruit % in. , tipped with the slender curved style, very variable. 

 Sub-sp. DEMER'SUM proper ; fruit smooth, spurs 2 subulate. C. apiculatum, 



Cham. 

 Sub-sp. SUBMER'SUM, L. (sp. ) ; fruit not spurred, covered when mature with 



cylindric projections. S.E. of England, rare. 



ORDER LXX. 



Herbs, shrubs, or trees ; juice watery. Leaves opposite or alternate, 

 stipulate or not. Flowers 1 -sexual, small, green. MALE. Calyx 4-5- 

 partite, concave. Stamens 4-5, opposite the sepals, filaments transversely 

 furrowed, inllexed in bud, springing up elastically ; anthers fixed at the 

 back, bursting inwards. Ovary rudimentary. FEMALE. Calyx tubular 

 or 3-5-cleft. Staininodes 3-5 or 0. Ovary sessile, ovoid, 1-celled ; style 

 Dimple or 0, terminal or lateral, stigma lateral or terminal glandular or 

 penicillate ; ovule basal, erect, orthotropous. Fruit minute, dry or fleshy, 

 indehiscent, free or adhering to the calyx. Seed erect, testa thin, albumen 

 lleshy usually scanty ; embryo axile, straight, cotyledons plano-convex, 

 radicle superior. DISTRIB. All climates ; genera 43 ; species 500. 

 AFFINITIES. With Ulmacccc, Cannabineai, Malvaceie, and Eujrfiorbiacece. 

 PROPERTIES. The inner bark affords valuable fibre. 



Leaves opposite, with stinging hairs 1. Urtica. 



Loaves al sernate, with simple hairs 2. Parietaria. 



