Class V. Order IL 69 



the odd one rhomboid, sessile, the lateral ones de- 

 cursive. Mich. 



A very large umbellate plant, well known for its fine aroma- 

 tic flavour. Stem large, five or six feet high, petioles with very 

 large swelling stipulse. Leaves smooth, decompound, the three 

 terminal leafets appearing as one. Seeds oblong-hemispheri- 

 cal, three winged on the back. Cambridge, meadows. June. 



86. SIUM. 

 SIUM LALIFOLIUM. L. Water parsmp. 



Leaves pinnate ; leafets oblong-lanceolate, 

 equally serrate. Sm. 



A tall aquatic plant common in ditches and muddy brooks. 

 Stem erect, hollow, smooth, with deep furrows and sharp, prom- 

 inent angles. Leaves pinnate ; leafets in half a dozen pairs, 

 with an odd one, ovate-lanceolate, equally serrate, or laciniated 

 if under water. Umbels solitary, mostly terminal. General 

 involucre of many leaves lanceolate, and occasionally serrate. 

 Partial involucres small. Flowers white. Fruit ovate, striated 

 From July to September. Perennial. 



87. SISON. 



SISON CANADENSE. L. Honeivort, 



Leaves ternate ; umbels irregular. 



Stem smooth. Leaves in threes, the radical ones cleft, those 

 of the stem doubly toothed, rhomboidal, shining. Umbel une- 

 qual, of four rays with no general involucre. Partial umbels 

 unequal, close, few flowered with a minute involucre. Flow- 

 ers small, white. Seeds smooth, oblong. Lynn beach island, 

 July. 



