REJUVENESCENCE IN NATURE. 91 



Boragineae (Myosotis, Ompkalodes linifolia), most of the 

 Hydrophylleae (Phacelia, Hydrophyllum canadense), Cistus 

 salviafolius and monspeliensis, Ulmaria palustris, &c. 



The suppression of the leaf-formation at the transition 

 into the flower may affect, as above remarked, not merely 

 the last section of the leaves preceding the flower, but 

 even the commencing formations of the flower itself. Thus 

 we see the calyx, at least its free portion, undeveloped or 

 appearing as a crown of hairs in the Composite, many 

 Umbelliferae, Rubiacece, and Valerianea?, while the corolla 

 is developed fully in these families. Calyx and corolla 

 are suppressed together in Fraxinus, while the nearly 

 related genus Ornus exhibits both; the same occurs in 

 many Amentacese, especially of the group of Betulacese.* 

 The perigone of the Monocotyledons is suppressed in 

 many Aroideas, e.g. in Call a, while it is visible in Potkos 

 and A 'cor -us ; in the Cyperaceae, also, where it frequently 

 presents itself in the form of bristles, which may be com- 

 pared to the pappus in the Composite ;f and, finally, in 

 the Grasses, in which, however, the inner circle of the 

 perigone, analogous to the corolla, comes to light, wholly 

 or partly, in the form of little scales (lodiculce). j 



* In Almts and Betula the calyx is indistinguishable in the female flower, 

 but visible in the male ; in Carpinus and Corylus, on the other hand, the male 

 flower is devoid of a visible calyx while the female possesses one. 



f The three scales in the flower oiFuirena do not belong to the perigone, 

 but correspond, as Nees correctly assumes, to the inner circle of stamens. 

 They stand decidedly inside and not outside the three fully-developed stamens. 

 See, for other points, the in other respects accurate description of the flower 

 of the Fmreiue,\)j Schlechtendal, ('Bot. Zeit.,' 1845, p. 849.) 



J The inner perigonial circle is perfect, composed of three little scales, in 

 Stipa and the Bambu^ea; in most of the other grasses it is imperfect, the 

 leaf falling posteriorly being suppressed. Sometimes the abortion extends to 

 the inner circle of the perigoue, as in Crypsis, Alopecurus. As regards the 

 foundation for the assumption of an outer, constantly abortive perigonial 

 circle, it can only be observed here that it is derived from the comparative 

 study of the rudiments of the branches of the monocotyledons and the rules 

 of insertion of lateral flowers dependent thereon. Under the hypothesis 

 that it possesses a double perigone, the flower of the Grasses stands in the 

 axil of its bract exactly like the bracteolate flower of the Iridese. The same 

 attachment of the flower is probably to be assumed of the Cyperacese also, 

 only in this family the bracteole (the inner palea) is constantly suppressed, 

 while in the Grasses it is fully developed, except hi a few cases (Trickodium, 

 Alopecvnti). 



