428 AL1SMACEJE. [Damasonium. 



Gravelly ditches and pools, rare, from Salop and Suffolk to Kent and Hants ; 

 fl. May-July. — Leaves many, 2 in., obtuse, floating or emersed; petiole stout, 

 2-5 in. Scape 4-6 in., stout, with usually 2 whorls of flowers ; pedicels 1 in. 

 Flowers f in. diam. ; petals caducous. Fruit § in. diam., carpels dehiscing 

 ventrally. — Distrib. France, Spain, Italy, N. Africa. 



4. SAGITTA'RIA, L. 



Habit and inflorescence of Alis'ma, but flowers 1 -sexual ; stamens 

 numerous ; anthers basifixed, dehiscence lateral. — Distrib. Temp, and 

 trop. ; species about 15. — Etym. sagitta, an arrow. 



S. sagittifo'lia, L. ; leaves hastate obtuse or acute. Arrow-head. 

 Ditches, canals, &c, from Cumberland to Kent and Devon; naturalized in 

 Scotland ; local in Ireland ; fl. July-Sept. — Stem swollen at the base, stoloni- 

 ferous ; stolons producing globose winter tubers § in. diam. Leaves 2-8 in., 

 erect, lobes long more or less diverging acuminate, the first developed sub- 

 merged, pellucid, linear ; petiole 8-18 in., stout, 3-gonous. Scape 6-18 in., 

 with 3-5 distant whorls of 3-5 flowers each ; bracts short, obtuse, mem- 

 branous; lower whorls female, pedicels short; upper male with longer 

 pedicels. Flowers § in. diam., males larger. Petals white, caducous, claw 

 purple. A nthers purple. Ripe carpels numerous, much compressed laterally, 

 obliquely obovate, apiculate, wings broad thick, cell small. Seeds as in 

 Alis'ma. — Distrib. Europe (Arctic) (excl. Greece), N. Asia, N.W. India. 



5. BU'TOMUS, L. Flowering Rush. 



A tall marsh herb, liootstock creeping. Leaves slender, erect. Scape 

 naked. Flowers in a bracteate umbel. Perianth-segments 6, oblong, 

 spreading, subequal, all coloured. Stamens 9, hypogynous, 6 in pairs 

 opposite the outer segments, 3 opposite the inner, filaments subulate ; 

 anthers basifixed, oblong, introrse. Carpels 6, beaked, connate below ; 

 styles short, stigmas sessile ; ovules covering the walls of the] carpel, 

 anatropous, ascending. Follicles 6, beaked, coriaceous, turgid. Seeds 

 many, minute, ascending, testa thin furrowed ; embryo straight. — Distrib. 

 Kurope, N. and W. Asia, N.W. India. — Etym. obscure. 



B. umbella'tus, L. ; leaves long slender 3-quetrous, scape terete. 



Ditches and river-sides from York and Durham southd. ; naturalized in Scot- 

 land ; rare in Ireland ; fl. June-July. — Rootstock stout. Leaves 3-4 ft., base 

 sheathing, twisted. Flowers many, 1 in. diam., rose-red, proterandrous ; 

 pedicels 2-4 in. Anthers and carpels red. 



Order LXXXVII. naiada'CE^e. 



Marsh- or water-herbs. Rootstock usually creeping. Stems elongate 

 (rarely 0), jointed, branched, slender. Leaves often floating, alternate 

 or distichous, rarely opposite, £ sheathing at the base ; stipules 



