OUTLINES OF BOTANY. XXV11 



entire part passes gradually into the upper divided and more spreading part, 

 the distinction between the tube and the limb is drawn either at the point 

 where the lobes separate, or at the part where the corolla first expands, accord- 

 ing to which is the most marked. 



105. Irregular corollas have received various names according to the more 

 familiar forms they have been compared to. Some of the most important are 

 the 



bilabiate, or two-lipped corolla, when, in a four- or five-lobed corolla, the 

 two or three upper lobes stand obviously apart, like an upper lip, from the 

 two or three lower ones or under lip. In Orchidece and some other families 

 the name of lip, or labellum, is given to one of the divisions or lobes of 

 the perianth. 



personate, when two-lipped, and the orifice of the tube closed by a pro- 

 jection from the base of the upper or lower lip, called a palate. 



ringent, when very strongly two-lipped, and the orifice of the tube very 

 open. 



spurred^, when the tube or the lower part of a petal has a conical hollow 

 projection, compared to the spur of a cock ; saccate, when the spur is short and 

 round like a little bag ; gibbous, when projecting at any part into a slight 

 swelling. 



resupinate or reversed, when a lip, spur, etc., which in allied species is 

 usually lowest, lies uppermost, and vice versa. 



106. The above terms are mostly applied to the forms of monopetalous 

 corollas, but several are also applicable to those of polypetalous ones. Terms 

 descriptive of the special forms of corolla in certain Natural Orders, will be ex- 

 plained under those Orders respectively. 



107. Most of the terms used for describing the forms of leaves (39, 45) are 

 also applicable to those of individual petals ; but the flat expanded portion of a 

 petal, corresponding to the blade of the leaf, is called its lamina, and the stalk, 

 corresponding to the petiole, its claw {unguis). The stalked petal is said to be 

 tm^uiculate. 



§ 10. The Stamens. 



108. Although in a few cases the outer stamens may gradually pass into 

 petals, yet, in general, Stamens are very different in shape and aspect from 

 leaves, sepals, or petals. It is only in a theoretical point of view (not the less 

 important in the study of the physiological economy of the plant) that they can 

 be called altered leaves. 



109. This usual form is a stalk, called the filament, bearing at the top an 

 anther divided into two pouches or cells. These anther-cells are filled with 

 pollen, consisting of minute grains, usually forming a yellow dust, which, when 

 the flower expands, is scattered from an opening in each cell. When the two 

 cells are not closely contiguous, the portion of the anther that unites them is 

 called the connectivum. 



110. The filament is often wanting, and the anther sessile, yet still the sta- 

 men is perfect ; but if the anther, which is the essential part of the stamen, is 

 wanting, or does not contain pollen, the stamen is imperfect, and is then said 

 to be barren or sterile (without pollen), abortive, or rudimentary (84), accord- 

 ing to the degree to which the imperfection is carried. Imperfect stamens are 

 often called staminodia. 



111. In unsymmetrical flowers, the stamens of each whorl are sometimes 

 reduced in number below that of the petals, even to a single one, and in several 

 Natural Orders they are multiplied indefinitely. 



112. The terms monandrous and polyandrous are restricted to flowers which 

 have really but one stamen, or an indefinite number respectively. Where several 

 stamens are united into one, the flower is said to be synandrous. 



