MARE S-TAIL FAMILY 



2. Myriophyllum. — Leaves mostly whorled, pinnate ; sepals 

 4, superior ; petals 4, or absent ; stamens 2, 4, or 8, often in separ- 

 ate flowers from the carpels, but on the same plant (monoecious) ; 

 carpels 4. 



3. CALLiTRiCHE.— Leaves opposite, entire; sepals and petals 

 absent ; stamen 1 ; carpels 4 (monoecious). 



1. Hippuris (Mare's-tail). — Glabrous, aquatic herbs, with 

 erect, unbranched, leafy stems; whorled, 

 narrow, entire leaves ; minute, axillary, solitary 

 flowers ; calyx forming a minute, indistinctly 

 2-lobed rim to the ovary ; petals absent ; 

 stamen 1 ; carpel 1, i-seeded ; fruit nut-like, 

 indehiscent. (Name from the Greek hippos, 

 a horse, oura, a tail.) 



1. H. vulgaris (Common Mare's-tail.) — 

 The only British species, a singular plant, with 

 erect, unbranched, jointed stems, tapering to 

 a point, bearing whorls of 6 — 10 narrow leaves 

 with hard tips, and inconspicuous flowers 

 sessile in the axils of the upper leaves, and 

 often without stamens. — Not uncommon in 

 stagnant water. Not to be confounded with 

 the genus Eqttisetum (Horse-tail), a plant 

 allied to the Ferns, which also has a jointed 

 stem and whorled, rigid leaves, but bears its 

 fructification in terminal cones. — Fl. June, 

 July. Perennial. 



2. Myriophyllum (Water Milfoil). — 

 Glabrous, submerged plants ; leaves mostly 

 whorled and pinnately divided into numerous 

 hair-like segments ; flowers small, solitary or 

 in spikes, the lower often apetalous and pistil- 

 late, intermediate ones perfect, and the upper 

 staminate, so that the inflorescence is poly- 

 gamous ; sepals 4, rarely 2, united, superior ; 

 petals 4, 2, or absent ; stamens generally 8, 

 rarely 2 or 4; carpels 4, with feathery styles ; fruit dividing into 

 4, nut-like, indehiscent, one-seeded cocci. (Name from the Greek 

 murios, countless, phullon, a leaf, from its much-divided leaves.) 



1. M. verticilldtum (Whorled Water Milfoil). — Rhizome creep- * 

 ing ; stems floating, leafy ; with short internodes ; leaves with 

 distant hair-like segments, collapsing when removed from the 

 water ; flowers white, in whorls of about 5 each, forming an 



HIPPURIS VULGARIS 



{Common Mare's-tail). 



