350 Excerpta Botanica. 



Corylus americana, Victor, plur. (non? Willd.*). — Corylus hetero- 

 phylla, Fisch. ! \. — Corylus Turtschaninovii, Bess, in Flora, 1834, 

 Beybl. vi. — Corylus bulbosa, Turtsch. (ex Bess., /. e\). — Corylus 

 alba, C. americana, C. arborea, C. Avellana, C. barcelonensis, C. 

 bicarpa, C. corymbosa, C. crispa, C. glomerata, C. grandis, C. he- 

 terophylla, C. laciniata, C. maxima, C. minor, C. nana, C. ovata, 

 C. pedemontana, C. pumila, C. rotunda, C. rubra, C. striata, C. 

 subconica, C. sylvestris, C. tenuis, and C. urticcefolia, Hortul. 

 Fruticosa, dumosa, v. rarius subarborescens et unicaulis. Cortice 

 laevigata v. demum rimuloso, nunquam deciduo. Foliis ssepiiis 

 suborbicularibus v. ovato-subrotundis. Involucris-fructiferis (sae- 

 pissime bipartitis) nucibus subbrevioribus, v. paulo longioribus 

 (rarius subdimidio longioribus) ; segmentis inciso-dentatis v. 

 palmatifidis, demum plus minusve patulis. 



The characters generally attributed to this species are, sti- 

 pules oval or oblong, obtuse ; leaves cordiform, orbicular, 

 acuminated; fructiferous involucre inciso-dentate, and spread- 

 ing at the summit. This definition, with the exception of 

 the inconstant characters, is no otherwise defective than in 

 seeming to indicate that the fructiferous involucre of C. Avel- 

 lana is not bi- or tripartite as that of C. Colurna, and that 

 this structure of the involucre constitutes the difference of 

 the two species ; but, as before mentioned, the involucre of 

 C. Avellana differs essentially from that of C. Colurna in its 

 segments being more or less patulous and not connivent ; 

 for in the most usual, and consequently the normal state, 

 the involucre of C. Avellana is likewise divided to the base 

 into two nearly equal segments; less frequently this involucre 

 is divided to the base on one side only, as in the Yoke-Elms, 

 (Charmes); and very rarely it is divided to the base in three 

 unequal segments. As to the other pretended distinctive cha- 

 racters of C, Avellana, they are as inconstant as those of C. Co- 

 lurna, and consequently are valueless as specific distinctions. 

 We shall therefore merely repeat, that the leaves, stipules and 

 nut of Qi Avellana present all the variations of form and size 

 above described ; that its fructiferous involucre varies in pu- 

 bescence like that of C. Colurna, and the hairs of the invo- 

 lucre, petioles, peduncles, and young shoots are in like man- 

 one of the commonest varieties in our woods, viz. with an involucre scarcely 

 as long as the nut, slightly or not at all glandulose, and slightly inciso-den- 

 tate. 



* The C. americana of Willd. (Spec.) has been since considered by its 

 author himself as a distinct species from C. americana, Mich., and he has 

 named it C. pumila. This is unknown to us, but, judging from the definition 

 of its author, it can scarcely be anything else but a new synonym of C. Avel- 

 lana. 



f We cannot detect any difference between C. heterophylla, Fisch., and 

 the ordinary C. Avellana. 



