BOTANICAL TERMS. 267 



TUBE ; the lower, narrow part, of a blossom of one 

 petal, by which it is fixed to the receptacle. [Plates 

 5. 10. and 16.] 



TUBER ; a solid fleshy knob, connected with fibres, in 

 a root ; the potatoe is a tuber, and is supposed to 

 be an imperfect underground stem, the eyes repre- 

 senting buds. 



U 



UMBEL ; an assemblage of flowers, in which a number 

 of slender fruit-stalks grow from the same centre, 

 and rise nearly to the same height ; so as to form a 

 flat surface at top : as in Hemlock, and Cow Pars- 

 nip. The separate fruit-stalks are often called the 

 Spokes of the umbel. 



UMBELLIFEROUS; a term applied to plants, which 

 produce their flowers in umbels. 



UMBELLULE (a little umbel). In many umbelli- 

 ferous plants, each spoke of the umbel has an um- 

 bellule at its end. 



UNDER-SHRUB ; a plant, in which the lower part only 

 of the stem is woody, but the upper part herba- 

 ceous, and dying every .year. 



VALVES ; the pieces that compose a seed-vessel. 

 [Wood-cut, page 1 94.] The pod of the Wall-flower 

 has two valves, with a partition between them. 

 [Plate 1.] 



The term is applied also to the projecting sub- 



