216 PEACTICAL BOTANY 



seed, and close to it is the small scar of the hilum : this 

 seed is of the anatropous type and is exalbuminous. 

 Peel off the leathery seed-coat, and note the parts of 

 the straight embryo, viz. 



1. The radicle directed towards the micropyle. 



2. The two cotyledons, fleshy as before. 



3. Between them the very small plumule. 



Very similar results will be obtained from the Almond, 

 in which, however, the testa is the relatively thin 

 brown covering. Compare also the Walnut, in which 

 the cotyledons are corrugated, and the seed of the Syca- 

 more, in which they are spirally rolled together, &c. 



(c) Examine the ripe fruit of the Sunflower (Heli- 

 anthus annuus}. The "seeds" sold for sowing are 

 really fruits (achsenia), including the products of 

 development of both ovary and ovule. It is a dry 

 inferior achaenium, with narrower basal, and broader 

 apical end : at the latter is a scar, where were inserted 

 the style and other floral organs. 



Compare fruits in situ on the floral receptacle. 



Dissect off the brittle pericarp, from the anatropous 

 and exalbuminous seed, which it incloses. 



Note the delicate seed-coat, and, within this, the 

 straight embryo, of which the radicle is directed 

 towards the micropyle (i.e. towards the base of the fruit), 

 and the two cotyledons towards the apex of the 

 fruit. 



Separate the two cotyledons, and note between them, 

 at their point of attachment together, the minute 

 plumule. 



(d) Compare the structure of the albuminous seed 

 of the Castor oil (Eicinus communis), observing externally 



