The Seed's Travelling Outfit 



189 



and of Urospertnum^ so nicely balance the fruits that they come 

 to rest with the radicle pointing downward. The styles of 

 Erodium and other members of the Geranium family coil 

 tightly and catch upon some object. In rainy weather they 

 untwist and screw the seed down into the soil. 



When walking through the veld, we come home with our 

 clothing covered with " burrs ". As we pick them off the 

 seeds are scattered far from home. Take a little time before 

 throwing them away to see by what ingenious methods they 

 have attached themselves. The spirally twisted legumes of 

 Medicago are furnished with a border of firm little grappling 

 hooks. The two sharp- 

 pointed awns of Bidens 

 pierce our clothing, and the 

 reflexed bristles prevent 

 them from brushing off 

 again. Fruits of Burr Weed 

 (Xanthium) and Klis Grass 

 {Setaria verticillatay Beau v.) 

 become very troublesome 

 when the fruits become fast- 

 ened into the wool of sheep 

 or goats. Fig. 188 shows 

 the " wool spiders " of the 

 "Grappling Plant" {Har- 

 pagophytum procumbens^ D. C. ) . 



Seeds of orchids and Streptocarpus are so light that a breath 

 of wind will blow them away. 



The whole plant of Brunsvigia breaks off close to the 

 ground, goes rolling over the veld, scattering the hard smooth 

 seeds as it tumbles along. 



Many seeds are covered with an edible pulp, and so are 

 scattered by birds or other animals. 



One species of Mistletoe, Viscum minimum^ Haw., a para- 

 site on Euphorbia^ is independent of outside aid. It grows 

 profusely within its host, but projects beyond the surface less 

 than half an inch and bears three flowers. When their 

 large berries ripen, without falling from the stem, they each 



Fig. i88. —Seed of Harpagophytum pro- 

 cumbensy D.C. (" Grapple Plant " or 

 •'Wool Spider".) 



