DICOTYLEDONS 



207 



reference to the other parts, and report in your notebook 

 as to the following points : 



Numerical plan Presence or absence of parts 



Symmetry Union of parts 



Regularity Position of ovary 



A flower put up on the plan of four, like the one just 

 examined, is said to be tetramerous, or four parted. The 

 cress or mustard family gets its botanical name, Crnciferce, 

 cross-bearers, from the four opposite petals, which have 

 somewhat the appearance, when viewed from above, of a 

 St. Andrew's Cross. The cruciferous flowers and tetra- 

 dynamous stamens are striking characteristics of this fam- 

 ily, which is so well marked that the merest beginner can 

 hardly fail to recognize any member of it. Notice that 

 its flowers belong to the hypogynous class. 



296. Dissection of an Epigynous Dicotyledon. Sketch a 

 blossom of quince, haw, pear, or apple, first from the out- 

 side, then from the inside, 

 and then in vertical sec- 

 tion, labeling the parts as 

 in your other sketches. 

 Notice how the ovary is 

 sunk in the hollowed- 

 out receptacle (Sections 

 74, 77). Where are the 

 other parts attached ? 

 Are they inferior or su- 

 perior ? Hold up a petal 

 to the light and exam- 

 ine its venation through 

 a lens. (Use for this 

 purpose a petal from a 

 flower that has stood in 

 red ink for two or three 

 hours. The cherokee 

 rose petals show venation beautifully.) 

 veined or net veined ? 



397-400. Flower and sections of pear: 

 397, cluster of blossoms, showing inflores- 

 cence; 398, vertical section of a flower; 

 399, ground plan of a flower; 400, vertical 

 section of fruit. 



Is it parallel 



