DICOTYLEDONS 205 



294. The Epigynous Arrangement. — In cases of this 

 kind, where the other organs appear to rise from the top of 

 the ovary, they are said to be epigynous, a word meaning 

 "upon the ovary." The same thing is expressed in a dif- 

 ferent way by saying that the ovary is itiferior, or that the 

 other organs are superior. To make the matter clear, the 

 two sets of terms employed for describing the position of 

 the ovary are given below in parallel columns. 



Hypogynous Epigynous 



Ovary superior Ovary inferior 



Calyx or perianth inferior Calyx or perianth superior 



The epigynous arrangement is considered to mark a 

 higher stage of floral development than the hypogynous, 

 which is characteristic of a more simple and primitive 

 structure. 



DICOTYLEDONS 



Material. — Blossoms of any convenient specimens of the mus- 

 tard family. Large flowered species are always best if they can be 

 obtained ; cabbage, mustard, turnip, and wall-flower are very good. 



Flowers of apple, pear, or quince, and of peach, plum, cherry, or rose ; 

 also of any member of the pea family, such as bean, pea, vetch, black 

 locust, wistaria, etc. 



295. Dissection of a Typical Flower. — Gently remove 

 the sepals and petals from a mustard or other cress flower, 

 lay them on the table before you in exactly the order in 

 which they grew on the stem, and sketch them. How many 

 of each are there, and how do they alternate with one 

 another .■" Sketch the pistil and stamens as they stand on 

 the receptacle ; how many of the latter are there .? Notice 

 that two of the six are outside and a little below the 

 others, alternate with the petals, while the other four stand 

 opposite them, as is natural if they were alternating with 

 another ring of stamens between themselves and the co- 

 rolla. Stamens arranged in this way are said to be tetra- 

 dynamons, that is, four stronger, or larger than the others. 

 Put a dot before two of the sepals in your first drawing to 



