420 GENTIAN ACE^. GENTIAN TRIBE. 



markable for its glaucous hue, and for its pairs of leaves, 

 which, are rather distant, being united at the base (con- 

 nate), with the stem passing through them ; hence its 

 name, Perfoliate. The flowers, which are large and 

 handsome, are of a pale yellow, and expand only during 

 sunshine. Fl. June, September. Annual. 



5. MENYANTHES (Buck-lean). 



1. M. trifoliata (Buck-bean, Marsh Trefoil). The 

 only species ; most common in spongy bogs, or in stag- 

 nant water. The only British plant belonging to the 

 Order which has divided leaves. The stem scarcely rises 

 above the soil or water in which it grows, but is over- 

 topped by the large ternate (composed of 3 leaflets) 

 leaves, which in shape and colour resemble those of the 

 Windsor Bean ; each leaf-stalk has a sheathing base, 

 opposite to one of which rises a compound cluster of 

 exceedingly beautiful flowers, which when in bud are of 

 a bright rose colour, and when fully expanded have the 

 inner surface of the corolla thickly covered with white 

 fringe. The root, which is intensely bitter, is said to 

 be the most valuable of known tonics. Fl. June, July. 

 Perennial. 



6. YILLARSIA. 



1. V. nymphoeoides (Water Villarsia). The only 

 British species. A rare, floating aquatic, found in some 

 of the still ditches communicating with the Thames, and 

 in a few other places. As its specific name implies, it 

 has the habit of a Water-lily ; the leaves are nearly 

 round ; the flowers large, yellow, and fringed. Fl. July, 

 August. Perennial. 



