154 BOTANY. 



cross-section of a mericarp (Fig. 435) the little mouths of 

 the four oil-bags of the back are seen, along with two 

 others in the face of the commissure. If you have diffi- 

 culty in finding these oil-bags, cut the carpel across, as 

 shown in 435, and look down upon it with your glass, and 

 perhaps their cut ends will be visible to you. A thin sec- 

 tion, moistened and seen under a microscope, reveals 

 them very distinctly. 



Collect all the plants you can find with this kind of in- 

 florescence and examine their flowers and fruit. In most 

 cases you will need your glass and much patience in doing 

 this ; but, if you can not discover all the minute details 

 of structure, you can, at least, tell whether the fruit of the 

 plant is like that of the cow-parsnip or not. 



EXERCISE LXVII. 

 Classification of Umbel-bearing Plants. 



The order Umbelliferae is thus described : 



CALYX, superior ; LIMB, obsolete, or entire, or a five- 

 toothed border. PETALS, five, mostly with the point in- 

 flexed, and along with the five STAMENS, inserted on the 

 outside of a fleshy, epigynous disk at the base of the two 

 styles. FRUIT, consisting of two carpels, called mtricarps, 

 cohering by their faces, the commissure separating when 

 ripe, and suspended from the summit by a prolongation of 

 the receptacle, called a carpophore ; each carpel is marked 

 by five primary ribs, and a variable number of intermedi- 

 ate or secondary ones, between which are found oil-tubes, 

 called vittce, filled with aromatic oil. SEEDS, solitary, ana- 

 tropous, with minute embryo in horny albumen. 



HERBACEOUS plants, with hollow, furrowed stems. 

 LEAVES, alternate, mostly compound, usually sheathing at 

 the base (Fig. 436). FLOWERS, in umbels, usually com- 

 pound, often with involucre and involucels (Fig. 437). 



So, you see, we have here a family of fifteen hundred 



