BOTANY. 125 



(sometimes only one by abortion), having a placenta on the ventral suture. 

 Seeds 00, imbricate, pendulous, usually comose (hairy) at the hilum ; 

 albumen thin ; embryo straight ; cotyledons leafy ; radicle superior. 

 Shrubs, or occasionally herbs, usually with milky juice, and often twining. 

 The leaves are usually opposite, sometimes alternate or verticillate, with 

 interpetiolary cilia in place of stipules. The gynostegium, staminal crown 

 or peculiar hooded (cucuUate) appendages, prolonged from the tube of the 

 filaments, which occur in many of the plants of this order, give a peculiar 

 aspect to their flowers. They inhabit chiefly warm and tropical regions, 

 but many species extend to northern climates. Many succulent species are 

 found in the south of Africa. Lindley enumerates 141 genera, including 

 910 species. 



Tribe 1. Ceropegiece. Pollinia upright. Examples : Ceropegia, Hoya, 

 Stapelia. Tribe 2. Gonolobece. Pollinia horizontal. Example : Gonolobus. 

 Tribe 3. Oxypetalece. Pollinia pendent, supported by winged processes, with 

 a lateral spur. Example : Calostigma. Tribe 4. AsclepiecB. Pollinia 

 pendent. Examples : Asclepias, Acerates, Enslenia. Tribe 5. Periplocece. 

 Pollinia granular. Granules four-lobed. Example : Periploca. Ti-ibe 0. 

 SecamonecB. Anthers four-locular, pollinia twenty, applied by fours to the 

 summit of the corpuscles. Example : Secamone. 



The milky juice with which plants of this order abound, is usually bitter 

 and acrid, sometimes mild, as in the Cow plant of Ceylon, Gymnema 

 lactiferum. The wax plant of greenhouses (Hoya carnosa) derives its 

 name from the peculiar appearance of the flowers. The stapelias are 

 remarkable for the odor of the blossoms, which resembles that of rotten flesh. 

 Flesh flies, it is said, are deceived to such an extent by the smell, as to 

 deposit their eggs on the plant. The most conspicuous species of the 

 United States is Asclepias cornuti (A. syriac^) knoxyn as silk or milk weed, 

 a plant of some economical value. In certain districts of Europe, as in 

 Silesia, it is cultivated on a large scale. The stem is rotted like hemp, and 

 yields a strong fibre ; the long silky hairs attached to the seeds are spun into 

 various fabrics with silk or cotton, or else used in pillows as a substitute for 

 down. Sugar has been extracted from the flowers, and the juice contains 

 an abundance of caoutchouc. The hairs of the seeds, when properly pre- 

 pared, afford an excellent gun-cotton, much superior to that from true cotton. 

 Cynanchum vincetoxicum (Europe) {pi. 64, ßg. 1) ; a, flower branch ; 

 b, natural size of the flower ; c, process of the stigma ; d, section of the 

 ovary ; e, pollen mass ; /, pistil ; g, seed vessels ; h, seed ; i, vertical section 

 of do. 



Asclepias cornuti (A. syriaca). Milkweed (United States) {pi. 64, fig. 2) ; 

 a, group of flowers ; b, corona ; c, the calyx ; d, stamina ; e, segments of 

 corona exhibiting some of the pollinia ; /, two attached pollen masses 

 magnified ; g, section of the seed vessel ; h, a seed ; i, vertical section 

 of do. 



Order 100. Oleace^, the Olive Family. Flowers », sometimes j?. 

 Calyx gamosepalous, divided, persistent. Corolla gamopetalous, hypogynous, 

 four-cleft, sometimes of four petals which are connected in pairs by means 



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