CLASS DIANDRIA. 131 



normal law, caused by some accidental circumstance in the 

 growth and development of the parts of the flower. The num- 

 ber of stamens is frequently half that of the divisions of the 

 corolla : the lilac has two stamens, and a/b2^r-parted corolla. In 

 a plant with three stamens, the number three or six usually 

 prevails in the divisions of the calyx, corolla, capsule, c^^c. A 

 knowledge of this fact will assist us in determining the class of 

 a plant : for example, if we have a flower whose calyx \\^%ji'OQ 

 or ten sepals, and the divisions of the corolla are the same, we 

 may expect, if the flower is a perfect one, to find either^y^ or ten 

 stamens ; or if the divisions of the flower be two^ there will gen- 

 erally be txoo or four stamens ; if tliree^ either three or six sta- 

 mens ; if foui\ Q\\h^YfoiLT or eiglit stamens. The number ^;;?^'^, 

 as divisions of the calyx, corolla, and capsule, is generally uni- 

 ted to five or ten stamens, and found in i\iQ fifth or tenth class. 



a. Another native plant of this class is the Veronica (Fig. 129, c). Of the sev- 

 enty species which this genus is said to contain, no nlore than six or eight are com- 

 mon to North America. The Veronica and the Circrea both turn black when dried; 

 although they do not add to the beauty of an herbarium, they are desirable in a 

 collection of plants, as our country contains few specimens to illustrate the second 

 CI3.SS of the LinnfBan system. 



h. Among the exotics of this order we find a singular plant, peculiar to the East 

 Indies, the Nvctanthes arbor tristis, or sorrowful tree ; its boughs droop during 

 the day, but through the night they are erect, and appear fresh and flourishing. 

 The Olive ( Olea) is common on the rocks of Palestine ; it may now, according to 

 the accounts of travelers, be found upon the same spot which was called eleven 

 centuries before the Christian era the Mount of Olives, or Mount Olivet. 



169. Order Digynia^ two pistils. — Contains the sweet-scent- 

 ed spring-grass (Anthoxanthum odoratiim)^ which is found in 

 blossom in May ; to this grass the pleasant smell of new-made 

 hay is chiefly owing ; its odor is like that of clover. This plant 

 is separated, by the artificial system, from the other grasses on 

 account of its havino; but two stamens. 



a. The Catalpa, an elegant tree with flat, cordate or heart-shaped leaves, is in- 

 digenous to the Southern United States ; its white flowers striped with purple 

 grow in panicles similar to the Horse-chestnut. Only one species is found in North 

 America. 



170. Order Trigynia^ three pistils. — Contains the genus 

 pirER, one species of which, the 7iigru7n^ is the common hlacJc- 

 pejyper. The cayenne-pepper belongs to the genus capsicum, 

 which is found in the eighth class. The flowers of the Piper 

 genus have neither calyx nor corolla ; the fruit is borne on a 

 spadix. The Piperacece family, or natural order, consists of but 

 the one genus. Piper, which contains many species. The Piper 

 cuheha contains a peculiar principle in its fruit which is laiown 

 in medicine as ewJeJ-pepper ; another species of this genus 



fl. Veronica--*. Nyctanthes— Olive.— 169. Second order— Catalpa.— 170. Order Trii;ynia— Pep- 

 per — First order of tlio third olass. 



