28 INTRODUCTION. 



as in the pink. The irregular polypetalous corolla is papilionaceous when 

 there are five petals, the upper and posterior of which is broad and dilated 

 (vexillum or standard) ; the two middle and lateral parallel to each other 

 (alee or wings) ; and the two lower also parallel and united below {carina or 

 keel). There are many other irregular forms, but it is impossible to class 

 them. 



Stamens are the male organs of a plant, and are situated within the floral 

 envelopes. They vary in number in different flowers. A stamen consists of 

 two parts, the filament and anther ; the former supports the latter, and is 

 a long slender body, containing numerous spiral vessels; it is said to be pro- 

 minent when it projects beyond the anther, petaloid when it is broad and thin. 

 They vary in number and position in different plants, but are usually more 

 numerous than the pistils. Where there is one stamen the plant is said to be 

 motiandrous, where two, diandrous (see classification) ; when four, of which 

 two are longer than the others, it is called didynamous ; when six, of which 

 four are longer, tetradynamous ; when united by their filaments, they are 

 called monadelphous, diadelphous, &c, according to the number of bun- 

 dles ipto which they are formed ; when they are united by their anthers, 

 they are called syngenesious ; when seated on the pistil, they are gynan- 

 droits. When stamens are longer than the corolla, they are termed exserted ; 

 when shorter included. The anther is the essential part of the stamen, and 

 p . 22 contains the pollen. It is of a cellular tex- 



ture, and usually consists of two cells or 

 lobes, attached to a prolongation of the fila- 

 ment called the connectivum. Its attach- 

 ment may be in one of three modes ; by its 

 back, when it is adnate ; by its base, when 



Various forms of stamens and anthers. j* is innate; or by a single point, SO as to 



aLiiium. b Lemma, c Soianum. d Berbe- hang loosely, when it is versatile; when 



the filament is on the outside of the anther, 

 so that this latter faces the pistil, it is termed introrse; when it looks away 

 from the pistil and towards the petals, it is called extrorse. Each lobe is 

 commonly marked with a furrow; this is the suture or line of dehiscence, by 

 which the anther opens ; but anthers may dehisce in other modes ; some open 

 by a transverse slip, some by pores or chinks at the apex; or by valves, 

 as in the Barberry, when the whole side of the cell is detached, and turns 

 back as on a hinge. Sometimes anthers are one-celled by the suppression of 

 one lobe, or by the disappearance of the partition. 



The pollen is a very fine powder, contained in the cells of the anther. It 

 consists of small vesicles containing a mucous fluid (fovilla) ; it is usually of 

 a yellow colour. The form of the vesicle or grains is usually spheroidal, but 

 occasionally cylindrical, many-sided, &c. They have two coats, the outer, 

 called extinc, and the inner, intine. The grains are generally distinct from 

 each other, but in Oenothera they are connected by cellular threads, and in 

 Mimosa arecoherent in small masses, and in the Orchidacea^and Asclcpiadaceai 

 are united in one or more groups, called pollinia. These, in the former 

 class, have an elastic stalk or caudicle. When ripe, the pollen grains burst, 

 and the inner membrane protrudes, constituting a channel for the transmis- 

 sion of the fovillce to the ovule. 



The disk is a ring, either entire or lobed, or a row of fleshy bodies, some- 

 times intervening between the stamens and pistils, around the base of the 

 latter, when it is hypo gy nous ; or partly covering the ovary, with the sta- 

 mens arising from it ; or adhering to and lining the tube of the calyx, when 



