262 BOTANY. 



marigold (follicle) ; 3, pea (legume) ; 3, mustard (capsule) ; 4, par- 

 snip (cremocarp) ; 5, oak (nut) ; 6, sunflower (achene) ; 7, Indian 

 corn (caryopsis) ; 8, melon or cucumber (pepo) ; 9, gooseberry (berry) ; 

 10, cherry (drupe) ; 11, apple (pome). Numbers 6 and 7, whicli are 

 popularly called seeds, are composed of a large seed enclosed in a 

 tightly fitting ovary- wall. 



{g) Study the Indian corn as an example of a wind-pollinated (ane- 

 mophilous) plant. Note the position of staminate (in the tassel) and 

 pistillate (in the ear) flowers. Estimate the relative number of 

 pollen-cells, and ovules (one in each ovary). 



(A) Study the position of the nectar in clover (at the bottom of the 

 corolla), columbine (in deep sacs of the petals), and buttercup (on 

 glands at the base of the petals). 



(i) Examine flowers from several different plants of eyebrights 

 (Houstonia), puccoon (Lithospermum), and cultivated primrose. Ob- 

 serve that on some plants the flowers have long stamens and short 

 styles, while in others they are the reverse. By measurements the 

 anthers of the one form will be found to have exactly the height of 

 the stigmas of the other. Many other flowers show this dimorphism ; 

 a few show trimorphism, i.e., three forms. 



(j) Observe the flowering of spring beauty (Claytonia), and notice 

 that the stamens mature before the stigmas are ready for pollination. 

 Observe in like manner thistles and sunflowers in which also proter- 

 andry, as it is called, takes place. Now observe the flowering of the 

 strawberry and the apple, in which the pistils mature before the 

 stamens. This is known as proterogyny. Both proterandry and pro- 

 terogyny are included under the general term of dichogamy. 



(k) Observe the large early flowers of violets, which are dependent 

 upon insects for pollination. Notice that after a while none of these 

 appear, but only small ones destitute of petals. In the common yel- 

 low violet these are borne on the stem above the ground, but in blue 

 violets they are often underground. These small flowers are self- 

 pollinated (cleistogamous). 



497. The fibro-vascular bundles of the stems of Angio- 

 sperms are entirely of DeBary's ".collateral" class; that 

 is, each bundle in cross-section is more or less distinctly 

 two-sided, viz. , wood and bark. Bach of these sides gen- 

 erally contains soft, fibrous, and vascular tissues. 



498. The disposition of the bundles in the Angiosperms 

 is for the most part dependent upon the position of the 



