XVi OUTLINES OF 





does not contain pollen, the stamen is imperfect, and is then said to be barren or sterile 

 (without pollen), abortive, or rudimentary (84), according 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. 



113. Stamens are 



monadelphous, when united by their filaments into one cluster. This cluster either 

 forms a tube round the pistil, or, if the pistil is wanting, occupies the centre of the 

 flower. 



diadelphous, when so united into two clusters or phalanges. The term is more 

 especially applied to certain Leguminosce, in which nine stamens are united in a tube 

 slit open on the upper side, and a tenth, placed in a slit, is free. In some other plants 

 the stamens are equally distributed in the two clusters. 



triadelphous, pentadelphous, polyadelphous, when so united into three, five, or 

 many clusters or phalanges. 



syngenesious, when united by their anthers in a ring round the pistil, the filaments 

 usually remaining free. 



didynamous, when (usually in a bilabiate flower) there are four stamens in two 

 pairs, those of one pair longer than those of the other. 



tetradynamous, when (in Crucifera) there are six, four of them longer than the 

 two others. 



exserted, when longer than the corolla, or even when longer than its tube, if the 

 limb be very spreading. 



114. An Anther (109) is 



adnate, when continuous with the filament, the anther-cells appearing to lio their 

 whole length along the upper part of the filament. 



innate, when firmly attached by their base to the filament. This is an adnate 

 anther when rather more distinct from the filament. 



versatile, when attached by their back to the very point of the filament, so as to 

 swing loosely. 



115. Anther-cells may he parallel or diverging at a less or greater angle ; or diva- 

 ricate, when placed end to end so as to form one straight line. The end of each an- 

 ther-cell placed nearest to the other cell is generally called its apex or summit, and 

 the other end its base (36) ; but some botanists reverse the sense of these terms. 



116. Anthers have often, on their connectivum or cells, appendages termed bristles 

 (setse), spurs, crests, points, glands, etc., according to their appearance. 



117. Anthers have occasionally only one cell : this may take place either by the dis- 

 appearance of the partition between two closely contiguous cells, when these cells 

 are said to be confluent ; or by the abortion or total deficiency of one of the cells, when 

 the anther is said to be dimidiate. 



118. Anthers will open or dehisce to let out the pollen, like capsules, in valves, pores, 

 or slits. Their dehiscence is introrse, when the opening faces the pistil ; extrorse, when 

 towards the circumference of the flower. 



1 19. Pollen (109) is not always in the form of dust. It is sometimes collected in each 

 cell into one or two little wax-liko masses. Special terms used in describing these 

 masses or other modifications of the pollen will be explained under the Orders where 

 they occur. 



§ 11. The Pistil. 



120. The carpels (91) of the Pistil, although they may occasionally assume, rather 

 more than stamens, the appearance and colour of leaves, are still more different in 

 shape and structure. They are usually sessile ; if stalked, their stalk is called a podo- 

 carp. This stalk, upon which each separate carpel is supported above the receptacle, 

 must not be confounded with the gynobasis (143), upon which the whole pistil is 

 sometimes raised. 



