FRUITS AND SEEDS 197 
stroyed, but some are carried away and dropped, others 
stored in holes and forgotten. 
(b) Adhesive fruits and seeds become attached to the 
hairy coats of animals, and may be carried considerable 
distances before they are finally dropped or rubbed off. 
In burdock the achenes are smooth, but the involucral 
bracts enclosing the head are hooked; the fruits of 
cleavers (Galium Aparine) and enchanter’s - nightshade 
(Circeea lutetiana) are covered with short stiff bristles ; 
the achenes of avens (Gewm) are hooked (Fig. 106). In 
Bidens (the bur-marigold), the achenes are armed with 
barbed prongs (Fig. 107); in agrimony the receptacle is 
covered on the outside with hooked bristles. 
5. Water-Borne Fruits and Seeds.—Aquatics which 
flower and fruit under water must obviously have their 
naam y 
f 
Fic. 105.—Drniscep Fic. 106.—AcHENnEor Fic. 107. — ACHENE 
CAPSULE OF VIOLET. AVvENS (Geum), WITH (CypsELA) oF Bur- 
Hooxrp StryLe. Maricoup (Bidens). 
seeds dispersed by water. Seeds dropped into water 
may float and be carried some distance and washed up on 
land. Dry fruits often contain a considerable amount of 
enclosed air. If such fruits fall into water, they float and 
may be driven along the surface of the water by the wind. 
In this case the agent of distribution is the wind, not the 
water. Few special structures for water-dispersal are 
found among English fruits. In the white water-lily, 
however, the fruit is a large berry, containing a large 
number of seeds. Each seed is surrounded by a spongy 
aril, containing cavities filled with air. When the fruit 
opens, the seeds float up to the surface of the water, 
and are drifted about until the aril rots, when they sink. 
In fresh water seeds may germinate while floating on the 
surface—e.g., willowherb. If driven ashore by the wind, 
they may continue to live. 
