132 THE FLORA OF THE ALPS 



ceolate, stipules ovate-lanceolate, deciduous. 6". Caprea, 

 L., Sallow; leaves elliptic, tomentose beneath; a small 

 tree. S. aurita, L. ; leaves obovate-oblong, catkins short, 

 dense-flowered. 6". viminalis, L., Osier; leaves linear- 

 lanceolate, catkins sessile, branches very flexible. S. 

 purpiirea, L. ; leaves linear-lanceolate, catkins with purple- 

 black scales. 



Division IL — MONOOOTYLEDONES or ENDOGENS. 



Stem, when perennial, with irregularly dispersed woody 

 bundles, not in concentric circles, with no central pith 

 or separable bark ; leaves usually parallel-veined ; sepals, 

 petals, and stamens usually in threes ; embryo with one 

 cotyledon. 



Class V.—PETALOID^. 



Calyx and corolla usually both present and coloured. 

 (Orders LXXXIV.-XCIX.) 



Order LXXXIV.— HYDROCHARIDEiE. 



Aquatic herbs with floating or submerged opposite or 

 whorled leaves; flowers usually unisexual and dioecious, 

 buds enclosed in spathes ; perianth 6-parted, coloured or 

 inconspicuous; stamens 3-12; ovary i-6-celled. Avery 

 small order, widely distributed ; not alpine. 



I. Hydrocharis, L. 

 Dioecious ; sepals 3, green ; petals 3, white ; stamens 

 12, some of them imperfect; ovary 6-ceIled; styles 6; 

 leaves orbicular, entire. 



