CARYOPHYLLEAE 175 



they assume a horizontal or completely extrorse position. The styles and stigmas in 

 roost species are not fully developed when the flower opens, or at the time the 

 shedding of pollen begins. 



In some species, however, the stigmas are regularly mature and receptive during 

 the dehiscence of the outer or at any rate of the inner anthers. In other species the 

 stigmas are mature only when the inner stamens have discharged almost all their 

 pollen, and in yet other species — e.g. Alsine verna and Stellaria graminea — they 

 become receptive only after all the empty inner anthers, or at least those of them 

 which first dehisce, have fallen to the ground. There are but few species in which 

 the stigmas are receptive when the outer anthers are beginning to open. Automatic 

 self-pollination is almost inevitable in those species where the stigmas are receptive 

 while the anthers of the outer stamens — which often bend inwards — are dehiscing. 

 Self-pollination is much less likely when the stigmas first mature while pollen is 

 being shed from the anthers of the erect or more or less outwardly inclined inner 

 stamens. It is, of course, quite impossible when the stigmas become receptive only 

 after the anthers have lost their pollen, or when all or some of them have fallen to 

 the ground. The hermaphrodite flowers of but few species regularly possess the 

 typical number of stamens : in most species some or all of the inner stamens are 

 wanting in a larger or smaller proportion of the flowers, and less frequently one, two, 

 or even three of the outer stamens are absent. In some species the normal number 

 of stamens is rare, in a few it is very rare, and in a small percentage it seems never 

 to have been observed. In almost all cases — Moenchia erecta and Moehringia 

 trinervia apparently alone excepted — female flowers make their appearance, being 

 far more numerous in species which possess the typical number of stamens than in 

 those which rarely or never do so. The female flowers are usually to be found 

 on separate plants. They are much less frequently — in some species but very rarely 

 — associated with hermaphrodite flowers on the same stocks. In some species, 

 however, such an association is almost always the rule. The female flowers are 

 smaller than the hermaphrodite ones, but in nearly all species both kinds often vary 

 greatly in size. In female flowers the stamens have either entirely disappeared 

 or are reduced to more or less considerable vestiges. In the latter case remains 

 of the anthers commonly occur, the largest of these being often but little smaller 

 than the normal and typical ones. They are almost always white or discoloured 

 yellow, but now and then contain a few normal pollen-grains capable of germination, 

 as well as small abnormal polyhedral or rounded ones. The styles of female flowers 

 are often somewhat longer, and stigmas stouter, closer, and beset with longer papillae, 

 than those of hermaphrodite ones. In almost all Alsineae there is a tendency for the 

 flowers to close more or less completely — or at least to contract — during the night, 

 and in cool, moist weather. In many species when the flowers close completely at 

 night, and in bad weather, they remain open all day when the weather is bright and 

 warm. In other species the flowers remain open in such weather only during the 

 middle of the day, while in some species, e.g. Sagina Linnaei, var. macrocarpa, it 

 appears that they only open when there has been warm weather for at least five 

 or six hours previously. Other species, again, such as Sagina Linnaei, var. micro- 

 carpa, and Stellaria media, var. pallida (S. Boraeana/or^/.), have taken a further step 

 towards cleistogamy, for they frequently do not open even during long periods of 



