THE APETALOUS ORDERS. 469 



the genus Callitriche ; aquatic annuals, with opposite entire leaves ; 

 the axillary flowers (either perfect or monoecious) with a two- 

 leaved involucre, but entirely destitute of calyx and corolla ; sta- 

 men one (or rarely two), hypogynous, with a slender filament, and 

 a reniform one-celled anther; the ovary four-lobed, four-celled, 

 indehiscent in fruit ; the seeds albuminous. 



874. Ord, PodostemaceSB (the River-weed Family) comprises a 

 few (American and Asiatic) aquatics, with the aspect of Mosses or 

 HepaticaB ; their small flowers arising from a kind of spathe ; the 

 calyx often entirely wanting ; the stamens frequently reduced to 

 one, -or two and monadelphous ; the ovary two- or three-celled, 

 with distinct styles ; in fruit forming a ribbed capsule, containing 

 numerous exalbuminous seeds attached to a central column. Ex. 

 Podostemum. 



875. Ol'd, EuphorMaceae (the Spurge Family). Herbs, shrubs, or 

 even trees, often with a milky juice : in northern temperate climes 

 chiefly represented by the genus Euphorbia (Fig. 344-349); 

 which is remarkable for having numerous staminate flowers, re- 

 duced to a single stamen (484), inclosed in an involucre along 

 with one pistillate flower, reduced to a compound pistil, and also 

 achlamydeous, or with an obsolete calyx. But other genera have 

 a .regular calyx both to the staminate and pistillate flowers ; and a 

 few are likewise provided with petals. Ovary of two to nine more 

 or less united carpels, coherent to a central prolongation of the 

 axis : styles distinct, often two-cleft. Fruit mostly capsular, sep- 

 arating into its elementary carpels, or cocci (usually leaving a per- 

 sistent axis), which commonly open elastically by one or both 

 sutures. Seed with a large embryo in fleshy albumen, suspended. 

 Ex. Euphorbia (Spurge), Croton, Buxus (the Box). Acrid 

 and deleterious qualities pervade this large order, chiefly resident 

 in the (usually) milky juice. But the starchy accumulations in 

 the rhizoma, or underground portion of the stem, as in the Man- 

 dioc or Cassava (Janipha Manihot) of tropical America, are per- 

 fectly innocuous, when freed from the poisonous juice by washing 



stems sometimes woody, but scarcely exhibiting annual layers. They all 

 possess stimulant, aromatic, and pungent qualities, the common Pepper (the 

 dried berries of the Indian Piper nigrum) representing the ordinary properties 

 of the order. The intoxicating Betel of the Malays consists of the leaves of 

 Piper Betle. The Ava of the Society and Sandwich Islands, from which an 

 inebriating drink is made, is Piper methysticum. 

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