REJUVENESCENCE IN NATURE. 85 



which affords a certain justification of the old appHcation 

 of the name " compound flower," to the capitule of the 

 Compositse and the spikelet of the Grasses. If we examine 

 the order of capitulous-flowered plants (Compositse) in 

 reference to this point, we find hypsophyllary forma- 

 tion but seldom exhibiting a mere decreasing condition 

 of the leaf-formation, for the involucres or "common 

 caHces " are mostly formed of hypsophyllary leaves larger 

 than those immediately preceding them on the stalk,* 

 and within the involucre itself there mostly occurs a 

 further increase of size of the successive involucral-leaves, 

 as is shown in the so-familiar "involucra calyculata" 

 and " imbricata."! This phenomenon is truly splendidly 

 exhibited in the coloured, radiantly expanded involucres 

 of Carlina, Xeranthemum, and Helichrysum. In the 

 last-named genus {e.g. in H. proHferum), we even find 

 the rare case of hypsophyllary formation far exceeding in 

 its ascent the size of the euphyllary leaves. After the 

 maximum is attained the hypsophyllary formation sinks 

 down again, upon the main axis, to the form of little 

 paleae or teeth, often passing into a fibrous dissolution, 

 frequently at last vanishing altogether, (receptaculum 

 paleaceuni, denticMlatum, Jibrillosuni, nudum.) I will 

 describe somewhat minutely in this respect Calliopsis 

 Mcolor, an ornamental plant generally diff'used in gardens, 

 as an example. Cataphyllary leaves are absent. We find 

 the leaf-formation advancing, on the abbreviated base of 

 the stock, from simple to simply pinnatifid and bipinna- 

 tifid euphyllary leaves. On the ascending part of the 

 stem follows a decreasing series of small-lobed bipinna- 

 tifid, simply pinnatifid, and at last simple euphyllary 

 leaves, which form the transition to a few very small 

 linear, brownish-coloured hypsophyllary leaves scattered 

 on the stalk of the capitule. The 8 outer leaves of the 

 involucre are already somewhat larger, especially broader, 



* See, for instance, Hieraciuiii suhaudmn and allied species, Leontodon 

 squamosus, Gatananche car idea. 

 f ^x. gr. Glirysanthenmm Leuccmthemiim, Taraxacum, Scorzonera, Cynara. 



