1852 



A TEXTBOOK OF THEORETICAL BOTANY 



Asia and North Africa. The inflorescence is much reduced and may 

 consist of only a single flower. The leaves are simple and peltate. 

 Asorella contains about seventy species of cushion-like plants, found only 

 in the southern hemisphere. 



The pollination of Hydrocotyle vulgaris (Fig. 1756) is apparently by 

 minute flies. The flowers are extremely inconspicuous and self-pollination 

 often takes place. The anthers dehisce first in slow succession and the 

 stigma matures before the last anther has discharged its pollen. In fact, 

 it automatically comes into contact with the last stamen, so that, unless 

 cross-pollination has occurred before, self-pollination is automatic. The 

 nectar is completely exposed. 



Fig. 1757. — Eryugium. Pollination. Stamens developed first, then dropped. 

 In C the stigmas exppnding. (After Kmith.) 



In the Saniculoideae the best-known genus is Erynghim, (Fig. 1757), 

 with 220 species in temperate and subtropical regions. The flowers are 

 blue and are visited by bees. The inflorescence is surrounded by a spiny 

 involucre which prevents soft-bodied animals reaching the nectar by climb- 

 ing up the flowers (Fig. 1758). The stamen filaments are incurved in the 

 bud so that the anthers are enclosed in the corolla which is itself long and 

 stiflF. Meanwhile the ten-rayed disc begins to secrete nectar. First the 

 anthers uncurl and project beyond the corolla and then the tips of the petals 

 also uncurl so that only long-tongued insects can force their w'ay to the 

 nectar and in the process they become dusted with pollen. 



After the anthers have shed their pollen and dropped off, the style 

 elongates and the stigmatic branches diverge beyond the petals so that they 

 are in a suitable position to be pollinated by a visiting insect. 



Eryugium pandanifolium is of economic importance, for the leaves 

 yield Caraguata fibre. It belongs to a group of species in which the foliage 

 is reduced to a radical cluster of long phyllodes with toothed margins. 

 Their linear form and parallel venation give to the plants the aspect of 

 Monocotyledons. 



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