Lemna.] DIANDRIA — MONOGYKIA. il 



preceding : but is much smaller, the leaves decidedly cordate and the 

 petioles longer. Fruit, which is abundant oa C. Lutetiana, I have 

 never observed on this plant. 



8. Fbaxinus. Linn. Ash. 



1. F. excelsior, L. (commo^i Ash) ; leaves pinnated, leaflets 



ovato-lanceolate acuminate serrated, flowers witliout either calyx 



or corolla. E. Bot. t. 1692. — /3. heterophylla (simple-leaved 



Ash) ; leaves simple and pinnated. F. heterophylla, Vahl. — 



E. Bot. t. 2476. — F. simplicifolia, Willd. 



Woods and hedges throughout the country — /5. Rare in England. 

 I have specimens, from Mrs Griffiths, gathered in Devonshire. Fl. 

 in April and May, before the leaves appear. Tj . — One of the noblest 

 of our trees, remarkable in old individuals for the curving upwards of 

 the extremities of their lower pendent branches. There are many vari- 

 eties. The weeping Ash is said to have been first discovered in a field 

 at Gamlingay. By Lochlomond side the trees vary much in the width 

 of the leaflets, some have them all ovate, others quite lanceolate. The 



F. heterophylla may be considered a sort of monstrosity, often with the 

 leaflets united so as to form one single leaf. — The flowers are very sim- 

 ple. There is no calyx or corolla. The pistil and stamens, often one 

 of each, are sometimes separate, and rise at once from the extremity of 

 the flower-stalk. The wood is valuable for many purposes, especially 

 for implements of Imsbandry, the young copse-wood for making hurdles, 

 and the older for hop-poles. The roots are injurious to pastures by 

 their spreading to a great extent, and extracting the nourishment from 

 the soil. 



9. Lemna. Lhm. Duckweed. 



1. L. trisulca, L. {Ivy-leaved Duckiueed) ; fronds thin ellip- 

 tico-lanceolate caudate at one extremity, at the other serrated, 

 roots solitary. E. Bot. t. 926. 



Clear stagnant waters. Less frequent in Scotland than in England. 

 Fl. June, July. ©. — Fronds h — J of an inch in length, pellucid at the 

 margins, reticulated. Roots solitary, tipped at the extremity, as are 

 those of the rare and beautiful aquatic, Fontederia azurea, with a small 

 sheath. 



2. L. minor, L. (lesser Duckweed) ; fronds nearly ovate 

 compressed, roots solitary. E. Bot. t. 1095. 



Stagnant waters, common. — Fl. July. ©. — About a line or a line 

 and a half long ; of a rather thick and succulent, but compact texture, 

 slightly convex beneath. This is the most abundant of all the species, 

 covering the surface of ditches and harbouring numerous insects and 

 moUuscae, the food of ducks and other waterfowl, whence the English 

 name of Duckweed. The young fronds constitute the Lemna arhiza 

 of the French authors. The capsule is single-seeded ; seed transverse, 

 with its hilum " directed towards the narrow end of the frond." Wilson. 



3. L. polyrrhiza, L. (greater Duckweed) ; fronds obovato- 

 rotundate compressed, roots numerous clustered. E. Bot. t. 2458. 



Stagnant waters. Flowers unknown in Britain. Q . — The largest of 

 all the species, half an inch long and nearly as broad, succulent, firm, 

 faintly striated ; a little convex below, where, and at the margin above. 



