DICOTYLEDONOUS PLANTS 181 



grained masses. Ovary free from the calyx-tube, of 2 carpels, 

 more or less united below but unconnected above ; styles 2 ; 

 stigmas 5-angled ; ovules several-many. Fruit consisting of 

 1 or 2 pods. The flowers are very liighly specialized for 

 pollination by insects (see below, under Asclepias). 



I. ASCLEPIAS, L. 



Perennial herbs. Flowers in simple (usually many-flow- 

 ered) umbels. Calyx small, 5-parted, its lobes reflexed. 

 Corolla deeply 5-parted, with reflexed lobes ; crown of hoods 

 and horns conspicuous (Fig. 20, A, B). Stamens with their 

 filaments united into a tube around the pistil and anthers 

 adnate to the stigma (Fig. 20, D, E) ; anther-cells 2, each cell 

 containing an elongated, pear-shaped, tough mass of pollen, a 

 mass from one anther always paired with one from the adjoin- 

 ing anther and each two together suspended from one of the 

 5 split glands on the angles of the stigma (Fig. 20, D, E). 

 Ovaries 2 ; styles very short. Pods 2 or sometimes 1 and the 

 other undeveloped. Seeds flat, each with a tuft of long, silky 

 hairs. The flowers are pollinated by insects, which get their 

 feet entangled in the clefts of the glands (Fig. 20, g) and 

 then carry off the pollen-masses. (See Mtiller, The Fertiliza- 

 tion of Flowers, pp. 396-399 inclusive.) 



1. A. purpurascens, L. Purple Milkweed. Stem 1-3 ft. high, 

 somewhat branched above. Leaves 4-6 in. long, elliptical or nearly 

 so, the upper ones taper-pointed, slightly velvety beneath, short- 

 petioled. Umbels terminal. Flowers ^ in. long, dark purple ; pedi- 

 cels shorter than the peduncle ; horn broadly scythe-shaped, with 

 the point bent sharply inward. Dry soil. 



2. A. Cornuti, Decaisne. Common Milkweed. Stem stout, 

 3-4 ft. high, finely downy. Leaves 4-8 in. long, oblong or nearly 

 so, downy beneath. Umbels terminal or nearly so. Flowers vary- 

 ing from purple or greenish-purple to whitish, numerous, with a 

 strong, sweet, but sickening odor. Hoods with a tooth on each side 

 of the stout horn. Common in rich soil. 



3. A. phytolaccoides, Pursh. Poke-leaved Milkweed. Stem 

 rather slender, 3-5 ft. high. Leaves 6-9 in. long, ovate or oval- 

 lanceolate, taper-pointed, short-petioled. Umbels several, mostly 

 lateral ; pedicels slender and drooping. Lobes of the coroUa 



