498 



HUTCHINSON'S POPULAR BOTANY 



FIG. 633. Trigonia 

 villosa. 



Seed covered with long 

 woolly hairs. 



furnished with hairy coronets which assist dispersion ; while those of the 

 Poplar and Willow (Populus, fig. 625, and Salix) are provided with a silky 

 fluff, which subserves the same purpose, Myriads of such seeds get stuck 

 in the soft muddy banks of rivers, where they are 

 sucked into the soil and quickly germinate. Much the 

 same happens in the case of the Cotton-grasses (Erio- 

 phorum), where the long silky hairs that represented 

 the perianth at flowering time (see fig. 557) remain at- 

 tached to the fruit and entirely surround it. When they 

 have been carried off by the wind and 

 sink among the sphagnum and other 

 marsh-plants, the delicate filaments get 

 clogged with moisture which at once 

 fixes the seed in a suitable situation for 

 the future plant and sets up the right 

 conditions for germination. 



Some seeds appearto be designed speci- 

 ally to impose upon animals and induce them to help in 

 the work of dispersion. Among our smaller herbs some, 

 like Cow-wheat (Mdampyrum), produce seeds that closely 

 resemble the cocoons of ants the so-called "ants'-eggs" 

 and these have been seen to be picked up by ants and 

 carried away to their nests, where, of course, they germin- 

 ate. But even birds are similarly imposed 

 upon. In the case of a grain-eating bird 

 a seed eaten and passed through the grind- 

 ing apparatus known as the gizzard would 

 have little chance of ever escaping and 

 germinating ; but with insectivorous birds the conditions 

 are different. A seed that resembled a beetle or a small 

 caterpillar would form an attraction to such a bird, and 

 when swallowed would have every chance of passing un- 

 injured through the digestive tract and being voided at 

 some distance from the shrub upon which it was eaten. 

 Biserrula pelecinus produces a seed-pod that closely 

 resembles a centipede ; Martynia diandra has a seed which looks like a 

 beetle with long antennae ; the seeds of the Castor-oil plants (Ricinus) 

 are like swollen ticks, and those of Jatropha are exactly like the upper 

 side of a beetle. 



FIG. 632. Lepto- 

 dermis lanceolala 



An evergreen of Ben- 

 gal. A seed enclosed 

 in reticulated sac of 

 endocarp. 



FIG. 634. YEW. 



Section through ripe 

 seed and arillus. 



