364 VARIOUS PLANT GROUPS 



peach (Fig. 94, page 89), plum (Fig. 95, page 90), cherry 

 (Fig. 96, page 90), raspl)erry (Fig. 97, page 91), straw- 

 berry (Figs. 98 I-III, page 92), and roses (Figs. 148 II, 

 III, 298, pages 150, 151, 378), is seen to possess many 

 features of floral structure resembling more nearly those of 

 the crowfoot family than of any other family we have 

 studied. 



Note in the formulas of Rosa, Fragaria, Rubus, Primus, Cydonia, 

 and Pyrus, given on pages 408, 409, that the floral envelopes are 

 mostly in fives, while the essential organs are commonly numerous, 

 and that all are free and distinct, except sometimes the carpels, 

 which then, unlike poppy carpels, have axile placentae. 



An miusual form of calyx is found in strawberries (Fra- 

 garia). Here the sepals have stipules which coalesce in pairs so 

 as to form what looks like a calyx upon a caljTc , and is termed 

 'therefore an epicalyx.^ The only other features not before 

 encountered belong to the torus and the fruit. Throughout 

 the family the torus is concave or cup-like, and it is mostly 

 free as in peonies and our examples of the laurel family. In 

 roses (Rosa) it completely envelopes the carpels, and be- 

 comes fleshy and bright colored while the pericarps ripen 

 into hard nutlets,^ the wdiole forming a so-called "hip." The 

 strawberry fruit consists mainly of the upper part of the 

 torus,^ much swollen and bearing numerous achenes. Rasp- 

 berries have the upper part of the torus comparatively dry, 

 and in fruit the pericarps finally separate from it. As these 

 ripen, an outer layer becomes fleshy while an inner layer 

 hardens like an olive stone. A fruit in which the pericarp 

 is thus differentiated is called a "stone-fruit" or drupe.* In 

 raspberries and thimbleberries the little drupes coalesce 

 sufficiently to form a thimble-like mass after they separate 

 from the torus. In blackberries, on the contrary, the little 

 drupes remain attached to the part of the torus which bears 



' E"pi-ca'lyx < L. epi, upon. S ]. 



2 The hardening of the pericarp is expressed in the formulas by two 

 inverted exclamation marks. 



' A small t to represent part of the torus is used in the formulas instead 

 of the large capital. 



* Drupe < L. drupa, a ripe olive. C//.' 



