233 NATURAL HISTORY OF PLANTS. 



envelope,^ and which is an achene, the acorn^ inserted by a large, scar- 

 like surface at the bottom of its cupule,^ from which finally it gene- 

 rally separates,^ and surmounted by the remains of the superior calyx 

 and styles. Ordinarily it encloses only a single fertile descending 

 seed (fig. 188), accompanied, at a very variable point of its height,"^ 

 by five other seeds, small and sterile, and containing under its coats 

 a large fleshy embryo, destitute of albumen, with thick plano-convex 

 cotyledons, sometimes smooth and sometimes more or less wrinkled 

 or ruminated externally, and a short superior radicle, partly or en- 

 tirely concealed by the prolonged base of the cotyledons. 



There are Oaks in all parts of the northern hemisphere, both old and 

 new world, and some inhabit tropical regions. They are trees, rarely 

 of low elevation, with alternate leaves persistent or falling in winter, 

 accompanied by two lateral caducous stipules. The limb ^ is penni- 

 nerved, entire or more or less deeply cut, longitudinally plicate in 

 prefloration, and at first enveloped in buds with imbricate scales, 

 formed by the stipules^ (fig. 182). The inflorescences, ordinarily 

 unisexual, sometimes have female flowers at the base and males in 

 their upper portion, which are early detached. The male catkins, 

 pendent or erect, rise from the axil of the inferior leaves of the 

 young branches or of the bracts which replace them at this level, 

 oftener from lateral aphyllous or few-leaved buds. The female cat- 



cupule, formerly considered as formed of bracts a character noted by Michaux, in his IIi-«toire 



united together to a variable height, has been des Cheues, in 1801, and which has served to 



much discussed. It is now pretty well agreed distinguish certain species. The biennial ma- 



as to the axile nature of the body of the cupule turing is, perhaps, owing to defect of fecunda- 



itself, which Schacht calls a disk and Payer a tion in the first year. 



fold of the peduncle. We may, however, hesi- "* Sometimes near the base, as in Q. Hobur, 



tate as to the nature of the prominences it bears sometimes between the base and the middle, as 



and which often, by their form and anatomic in Q. Siiber, more frequently near the summit, 



structure, closely approximate to foliaceous {A.DC Biblioth. Univ. Gen. (Oct. 1862); Ann. 



organs, but which, by the same characters (the >Sc. Nat. ser. 4, xviii. 49.). 



value of which is insignificant), and also by ^ When young, like many other parts, it is 



their tardy appearance on the body itself of covered with stellate or fasciculate hairs, with 



the cupule, may appear equally comparable to some solitary, or ordinarily caducous, or cou- 



prickles. tractedin adult age (A. DC). 



^ There are species in which it divides supe- ^ Dcell, Zur Erklaer. d. Laubkn. Ament. 



riorly at maturity. (1848) ; Fl. Bad. ii. (on the morphological cha- 



- To which it sometimes adheres in its lower racter of the cupule). — YLY.-s\vL,Nov.Aet.]!fat.Cur. 



part. xxii. p. i. 337, t. 22. — H. Mcehl {Morphol. Unter- 



3 The fruit is matured sometimes in the year such. tieb. d. JEiche (1862), Cassel, in-4) has es- 



and sometimes, after a long repose, in the fol- tablished the disposition of the bracts of the 



lowing year. (J. Gay, £ulL Soc. Bot. de Ft: bud and the leaves in our indigenous species, the 



(1857), 445, 501 ; Ann. Sc. Nat. ser. 4, vi. 223) ; nervation of the leaves, etc. 



