ITS IRREGULARITY. 



253 



470. In some few plants the stamens continue this adnation a little 

 further, and cohere with the style, either with its base only, as in 

 some species of Asarum, or with its 



whole length, as in Cypripedium 

 (Fig, 468) and the whole Orchis 

 family. Then the flower is said 

 to be (fynandrous ; — from two 

 Greek words equivalent in mean- 

 ing to stamens and pistil com- 

 bined (519). 



471. Irregularity. The flower 



is irregular when the parts of its 

 different circles, or of one or 



more of them, are not all alike in number, 



shape, or size. Irregularity may be the re- 

 sult, therefore, either of the abortion or dis- 

 appearance of some parts, or of their tin- 

 equal developinent or unequal union. The 

 latter case may be first considered. 



472. The Pea tribe affords a familiar 

 illustration of irregular flowers arising from 

 the unequal size and dissimilar 

 form of the floral envelopes ; 

 especially of the corolla, which, 

 from a fancied resemblance to a 

 butterfly in the flower of the 

 Pea, Locust (Fig. 392), &c., has 

 been called papilionaceous. The 

 petals of such a corolla are dis- 

 tinguished by separate names ; 

 I b the upper one, which is usually 

 most conspicuous, being termed 

 the vexillum, standard, or banner 

 (Fig. 392', a) ; the two lateral 

 (b) are called uu'ngs (alee), and 

 the two lower (c), Avhich are 

 usually somewhat united along their anterior edges, and together 



FIG. 391. Flower of Cranberry divided lengtliwise, showing the petals and stamens epi- 

 gynous. 



FIG. 392. Front view of a flower of the common Locust-tree (Roblnia Pseudacacla). 



FIG. 392'. Corolla of the same, the petals displayed. 



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