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 (cucullate) 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. Ceropegiee. Pollinia upright. Iixamples: Ceropegia, Hoya, 
Stapelia. Tribe 2. Gonolobee. Pollinia horizontal. Example : Gonolobus. 
Tribe 3. Oxypetalee. Pollinia pendent, supported by winged processes, with 
alateral spur. Example: Calostigma. Tribe 4. Asclepiee. Pollinia 
pendent. Examples: Asclepias, Acerates, Enslenia. Tribe 5. Periplocea. 
Pollinia granular. Granules four-lobed. Example: Periploca. Tribe 6. 
Secamonee. 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. syriaca) known 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) (pl. 64, fig. 1); a, flower branch ; 
b, natural size of the flower; c, process of the stigma; d, ‘section of the 
ovary ; e, pollen mass; f, pistil; g, seed vessels; h, seed; 7, vertical section 
of do. 
Asclepias cornuti (A. syriaca), Milkweed (United States) (pl. 64, fig. 2) ; 
a, group of flowers; b, corona; c, the calyx; d, stamina; e, segments of 
corona exhibiting some of the pollinia; f, two attached pollen masses 
magnified; g, section of the seed vessel; h, a seed; 7, vertical section 
of do. 
Orper 100. Otzacea, the Olive Family. Flowers ¥, sometimes 3°. 
Calyx gamosepalous, divided, persistent. Corolla gamopetalous, hypogynous, 
four-cleft, sometimes of four petals which are connected in pairs by means 
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