68 



A SYNOPSIS OF THE PLANT KINGDOM 



cated. The union of the two carpels by the stigma only 

 is unique. 



Pleurisy root (Asclepias tuberosa) was formerly 

 used extensively for lung and catarrhal disorders. 

 Condurango, from the bark of Marsdenia Condurango, is 

 a stomach tonic. The milky juice of many is medici- 

 nal; some are emetics (Vincetoxicum, Gomphocarpus, 

 Secamone); others are purgative (Solenostemma, 



50. ASCLEPIADACE^:: 1. Asclepias, a, flower; 6, flower, vertical 

 section; <, stamens; d, pistil and pollinia; e, pollinia and gland; /, 

 floral diagram. CONVOLVULACE^E: 2. Convolvulus, floral dia- 

 gram. POLEMONIACE.E: 3. Phlox, flower. 4. Polemonium, floral 

 diagram. HYDROPHYLLACE.K: 5. Hydrophyllum, flower. 6. Phace- 

 lia, a, and 6, ovary of two species. 



Cynanchum); others are sudorifics (Hemidesmus). 

 The acrid juice of Gonolpbus is used to poison arrows; 

 that of Periploca to poison wolves, hence the name 

 wolfbane and dogbane. The milk of Gymnema 

 lactiferum, the cow-plant of Ceylon, is edible; also 

 that of the Cape, Oxystelma esculentum. Some Indian 

 species yield good bast fibers. 'Marsdenia tinctoria 

 yields a dye. Several species yield caoutchouc. The 

 oschur or modar (Calotropis procera) is probably the 

 sodom apple of the Bible. The herbage of several 

 species is cooked and eaten. The acid stem of Sarcos- 

 temma is eaten as a salad. In East Africa, Cynanchum 

 sarcostemmoides is used to poison fish. Many Ascle- 

 piadacese are ornamental plants. 



About 20 genera are in cultivation in N. America, 

 mostly in the tropical horticulture of Florida and 

 California. More generally cultivated and better 

 known are: Asclepias (Milkweed) ; Cynanchum (Mos- 

 quito Plant, Cruel Plant); Hoya (Wax-plant); and 

 Periploca (Silk Vine). 



Order 50. TUBIFIOILE 



190. Convolyulaceae (from the genus Convolvulus, 

 signifying to entwine). MORNING-GLORY FAMILY. Fig. 

 50. Herbs, shrubs or small trees, twining or erect, turf- 

 forming shrubs, thorny shrubs, "switch plants," or 

 yellow, leafless, twining parasites, often with milky 

 juice: leaves alternate: flowers bisexual, regular; pe- 

 duncles very often bi-bracteate; calyx 5-parted, per- 

 sistent; corolla more or less 5-lobed, usually plaited, 



gamopetalous, hypogynous, convolute; stamens 5, 

 slightly epipetalous, alternating with the corolla-lobes; 

 hypogynous disk present, usually lobed; ovary superior, 

 2-celled, rarely more or fewer celled; each cell 1-2- 

 ovuled, micropyle directed downward and outward; 

 styles 1-2; stigmas 1-2: fruit a capsule or a berry, very 

 rarely breaking into 4 1-seeded nutlets. 



Convolvulacese has 40 genera with about 1,000 

 species, of which 300 species belong to the genus 

 Ipomoea and 160 species to the genus Convolvulus. 

 They are distributed in all regions except the arctics; 

 but are especially numerous in tropical Asia and tropical 

 America. The family is related to the Solanacese and 

 Boraginaceae, but also to the Polemoniacese and Hydro- 

 phyllacese. The absence of a circinate inflorescence, 

 the plaited corolla, the direction in which the micropyle 

 is turned and the few-seeded fruit are important 

 distinguishing characteristics. The genus Cuscuta is 

 parasitic and chlorophylless, receiving its nutriment 

 by means of haustoria from the plant upon which it 

 twines. 



Because of the substances contained in the milky 

 juice, many species are medicinal. The following are 

 purges: jalap (Exogonium Purga), of Mexico; turbith 

 (Operculina Turpethum), of the East Indies; and scam- 

 mony (Convolvulus Scammonia), of the orient. The 

 fleshy roots of Ipomosa Batatas, (sweet potato) are edible; 

 also those of Convolvulus Sepium. Iponuea Pes-caprx 

 is used in India to bind the sands along the coast. 

 Convolvulus scoparius of the Canaries furnishes the 

 fragrant oil of rhodium, used to adulterate oil of rose, 

 and sold also to rat-catchers as a lure for rats. Cuscuta 

 Epilinum, and several other species, are bad pests in 

 cultivated fields. 



Several genera are in cultivation in N. America: 

 Argyreia, tender twiners; Breweria, trailing, grown in 

 Florida; Convolvulus (Bindweed, California Rose, 

 Rutland Beauty), mostly twining.; Ipomcea (Morning- 

 glory, Moonflower, Cypress Vine, Indian Pink, Man-of- 

 the-Earth, Blue Dawn Flower, Sweet Potato, Jalap), 

 mostly twining; Jacquemontia, garden twiners; Lett- 

 somia, twiners, grown in Florida. 



191. Polemoniaceae (from the genus Polemonium, an 

 ancient name of doubtful application). POLEMONIUM 

 FAMILY. Fig. 50. Herbs, rarely woody: leaves alter- 

 nate, or the lower sometimes opposite, simple or pinnate: 

 flowers bisexual, regular, or nearly so; calyx 5-cleft; 

 corolla 5-lobed, gamopetalous, hypogynous, convolute; 

 stamens 5, epipetalous, alternate with the corolla- 

 lobes; hypogynous disk present; ovary superior, 3-, 

 rarely 2- or 5-, celled; ovules in each cell many, rarely 

 1; style 1, 3-fid, rarely 5-fid; stigmas 3, rarely 5: fruit 

 a capsule. 



About 8 genera and 200 species are known; these 

 are almost entirely American and principally North 

 American. Nearly 100 species belong to the genus 

 Gilia. The family is closely related to the Convolvula- 

 ceac, and difficult to separate from that family. The 

 3 many-ovuled cells of the ovary are important. The 

 disk of Cobsea is large and 5-lobed. The terminal 

 leaflet of this plant is a branched tendril. 



Many Polemoniaceae are grown as ornamental 

 plants. Polemonium csmdeum (Jacob's ladder, or Greek 

 valerian) is used in some countries as a remedy for 

 various ailments. 



About 6 to 8 genera are cultivated in this country as 

 ornamental plants: Cantua, a shrub in the greenhouse; 

 Cobsea, a climbing herb, mostly in the greenhouse; 

 Gilia, many species, for bedding; Loeselia in the cool- 

 house; Phlox (Phlox, Ground or Moss Pink), for bed- 

 ding; Polemonium, for bedding. 



192. Hydrophyllacese (from the genus Hydrophyl- 

 Zura, meaning tcater-Zea/). WATER-LEAP FAMILY. Fig. 50. 

 Annual or perennial herbs: leaves mostly alternate, 

 often lobed: flowers bisexual, regular, mostly in circinate 

 raceme-like clusters; calyx 5-cleft; corolla 5-lobed, often 



