124 LABORATORY PRACTICE CHAP, xxxi 



III. Fruits with Tufts of Hairs. The achenes of many 

 of the Composite Family, particularly such as those of the 

 Dandelion {Taraxacum) , or the western Troximons {Agose- 

 ris), are provided with parasol-shaped tufts which act after 

 the fashion of a parachute. The student should examine 

 and draw as many of these as possible. (Examine also ripe 

 Thistle Heads.) 



IV. Seeds with Tufts of Hairs. Examine the dry seeds 

 of the Milkweed or of Cotton and notice the arrangement 

 of hairs and how they assist the seed in being carried by the 

 wind. Make sketches. 



V. Bladdery Fruits. Examine the ripe and dry fruits 

 of the Bladder Nut (Staphylea), of Isomeris, or of some 

 Astragalus species with swollen pods and notice : 



1. The general size, shape, color, etc. 



2. The much distended ovary wall. 



3. The buoyancy of the fruit. 



4. Make sketches. 



VI. Examine the dry, ripe fruits of the Hop, Hop Horn- 

 beam, or of the Ground Cherry (Physalis) and notice : 



1. The bladdery portion, either an enlarged investing bract 



(Hop) or the enlarged calyx {Physalis}. 



2. Make sketches and notes. 



VII. Tumble Weeds. Many species of plants which are 

 annuals dry up entirely upon the ripening of the seeds, 

 break away from their attachment, and are rolled about from 

 place to place by winds. They drop seeds as they travel 

 and thus often disperse their seeds over a very wide area. 



