DISPERSAL OF SEEDS, 146 
seeds, The genus Rumex (Dock) have all winged seeds, some of very 
curious shapes. The Mountain Sorrel has a seed with a large wing 
all round. The seeds of the Parsnip are winged. The Hop has an 
arrangement of bracts with the seeds at their base ; this is probably 
useful for the purpose of wind dispersal. THLASPI ARVENSE (Penny 
Cress) has a flat oval pod, with the valves winged all round, so it is 
possible for them to be blown away with some cf the small seeds 
still in them. There are some remarkable instances among foreign 
plants. In one Leguminous species the pod breaks up into winged 
sections; another has a wing at the extremity of the pod. 
We next come to seeds that have a hairy plume of some form or 
other to help them to fly through the air. These seeds are not 
confined to any particular order, but are most commonly found in 
the Composite. The hairs in this order form a tuft or crown on the 
top of the seed. This varies very much in form on different species. 
The two principal forms are pedunculate pappus and sessile pappus. 
The most elaborate of the former is that of TracgoPocon 
PRATENSIS (Jack-go-to-bed-at-noon), so called from its babit of 
shutting its infloresence at mid-day. This is on a long stalk, ard is 
a kind of fine net-work parachute, which carries the seeds along for 
a considerable distance, and when they strike the ground the thin 
stalk snaps and leaves the seed to germinate. The seeding heads 
are large, and a large number of seeds are released from each. The 
Salsify belongs to the same genus, and has exactly the same arrange- 
ment. If allowed to seed in a garden, it will be found the following 
Spring to have become quite a weed. 
The common Dandelion has also a stalked pappus, and I need 
hardly say makes the most of it to spread itself over the face of the 
land. It is not so elaborate as the last, but if you look carefully at 
it you will find that it is really a beautiful object. 
The Coltsfoot (Tussrraco Farrara) is an example of a sessile 
pappus. In this case the hairs are on the end of the seed without 
