THE LOWER DICOTYLEDONS. 319 



branch arises in the axil of each of the two leaves, this 

 branch bearing a pair of leaves and ending in a flower, and 

 so on. This branching may occur quite regularly as often as 

 six times, but as a rule the full number of flowers is not 

 formed every time of branching. 



The flower (1 to 2 cms. diam.) has five free sepals, five 

 petals twice as long as the sepals and each deeply notched, 

 ten stamens in two circles, and a rounded ovary with three 

 styles. The numerous ovules are on a free central axis. The 

 cup-like flower contains honey, secreted by glands at the 

 bases of the stamens on the receptacle and available to short- 

 tongued insects. 



The flower is protandrous, the two circles of stamens suc- 

 cessively rising and shedding their pollen before the styles 

 diverge. The inner surface of each style is covered with 

 stigmatic hairs, so that pollination does not occur until the 

 styles spread out and expose their stigma- surf aces. The 

 flowers are usually cross -pollinated by the various insect- 

 visitors, but self-pollination may occur as a last resort by the 

 spreading styles touching the anthers. 



The fruit is a thin- walled globular capsule, which splits at 

 the top into six teeth, the seeds being shaken out when the 

 wind rocks the plant about (censer mechanism). 



328. Common Chickweed (Stellaria media) is one of the 

 commonest and most variable plants, but is easily recognised 

 by the line of hair on the cylindrical stem, changing in posi- 

 tion at each " node." Water poured on the leaves runs down 

 these lines, which evidently serve to dry the plant after rain 

 and to convey water to the root, some of it probably being 

 absorbed at the " nodes," where it collects in a drop between 

 the bases of the opposite leaves. The leaves are ovate and 

 pointed, but variable in size ; the lower ones are stalked, but 

 the upper (those coming off above the first flower of the infl.) 

 are sessile. The flowers are much smaller than in Stitch- 

 wort ; the petals are generally shorter than sepals ; stamens 

 generally only three to five, rarely as many as ten. The plant 

 is a polycarpic annual, flowering all the year round ; in winter 

 the flowers are often cleistogamic, sometimes without petals, 

 and in any case are homogamous and self -pollinated in the 

 absence of insect- visitors (flies chiefly). 



