92 Introduction to Botany. 



Numerous ovules on a parietal placenta in each carpel. Anthers more 

 or less coherent and forming a closed tube around the carpels. Pollen 

 coherent in rather horny masses, called pollinia, the adjacent pollinia of 

 contiguous anthers being joined together by an inverted V-shaped, horny 

 excretion from the stigmatic disk (see Fig. 108). Nectar receptacles 

 occurring as a 5-lobed or parted crown or corona. 



I. ASCLEPIAS. Milkweed or Silkweed. 



(Gr., asklepios, god of medicine.) 



Herbs, usually with opposite or verticillate leaves. Each nectar 

 receptaele bearing an incurved horn within. Calyx usually small, divided 

 into 5 segments ; the 5 corolla segments reflexed when open. Anthers 

 tipped with a scale and winged along the sides. Seeds hairy-tufted in 

 all but i species (see Fig. 129). 



1. Asclepias tuberosa, L. (L., tuberosus, full of humps or lumps.) BUTTER- 

 FLY WEED or PLEURISY ROOT. Stems erect or ascending, hirsute-pubescent, 

 milky secretions not exuding when the stems are broken. Leaves alternate, 

 lanceolate-oblong. Flowers orange-colored in terminal cymose umbels. In dry 

 fields. 



2. Asclepias deciimbens, L. (L., decumbens, falling down.) DECUMBENT 

 BUTTERFLY WEED. Somewhat similar to the preceding species. Leaves elliptic 

 to oblong. Stems at first decumbent, but erect nearer the apex. In dry fields. 



3. Asclepias Cornuti, Decaisne. (L., cornutus, horned.) COMMON MILK- 

 WEED or SILKWEED. Stems erect and stout, 3 to 5 feet high, finely pubescent. 

 Leaves oval-oblong, pubescent beneath. Flowers greenish white with purplish 

 tinge, in dense umbels. Nectar receptacles exceeding the anthers, and incurved 

 horns. Follicles 3 to 5 inches long, tomentose and beset with soft spinose 

 processes. In rich -ground. 



II. ASCLEPIODORA. 



(Gr., asklepios, god of medicine; doron, gift.) 



Similar to Asclepias. but without horns from the nectar receptacles, 

 and with corolla lobes ascending or spreading. 



i. Asclepiodora viridis, Gray. (L., viridis, green.) GREEN MILKWEED. 

 Stems about i foot high, nearly or quite glabrous. Leaves ovate-oblong to lanceo- 

 late, short petioled, alternate. Flowers green with a purplish crown. In dry soil. 



CONVOLVULACE^. MORNING GLORY FAMILY. 



Mostly twining or trailing herbs, sometimes with milky secretions. 

 Leaves alternate. Flowers axillary, solitary, or cymose, regular and 

 perfect. Calyx 5-parted or divided. Corolla gamopetalous, generally 



