210 



WEEDS OF THE FARM AND GARDEN 



slender stem, numerous leaves, which are narrowly linear, 

 sessile and mostly whorled; flowers in umbels, greenish 

 white. 



Milkweed (Asclepias syriaca, L.). A perennial herb 

 with a stout stalk, growing from two to five feet high, 

 armed with fine, soft hairs; leaves oblong, oval or ovate, 



obtuse or roundish at the 

 base, the young leaf some- 

 what pubescent above, finally 

 becoming smooth, petioles 

 stout ; flowers borne in um- 

 bels, few to many, peduncles 

 hairy or tomentose ; corolla 

 a dull or greenish purple, oc- 

 casionally pale in color; fruit 

 a pod containing a large num- 

 ber of flattened seeds with 

 downy appendages which aid 

 in distributing the seed ; prop- 

 agated both by seeds and 

 "underground roots," and 

 said to be poisonous to stock. 

 Convolvulus Family (Con- 

 volvulaceae.) Contains twin- 

 ing or trailing herbs with a few shrubs or trees, some 

 having milky juice; leaves alternate without stipules; 

 flowers regular and perfect, calyx inferior, five-parted or 

 five-divided ; corolla five-lobed, plaited, convolute or 

 twisted in the bud ; stamens five, inserted on the tube of 

 the corolla and alternate with its lobes ; ovary two to 

 three-celled, with a pair of erect ovules in each cell. The 

 1,900 species of this family are widely distributed, but are 

 found chiefly in warm regions. Among them are several 

 economic plants, such as the sweet potato (Ipomoea 

 Batatas), which has been widely cultivated in all tropical 

 and sub-tropical countries. 



Fig. 135. Milkweed (Ascle- 

 pias syriaca). (C. M. King.) 



