RKJUVENESCENCE IN NATURE, 69 



closed sheaths, reaching down to the abbreviated sub- 

 terraneous portion of the stem ; these are followed mostly 

 by two sheaths, also closed round, but shorter, which 

 arise on the portion of the stem shooting up. The suc- 

 ceeding euphyllary leaves, further separated from each 

 other, and becoming progressively narrower and shorter, 

 are no longer embracing, and exhibit a gradual decrease 

 of the breadth of the base, following something like the 

 ratio I, I, I, I, I, I, I, i, and then remaining more equal, 

 decreasing to ^ as a minimum. The leaf embracing i 

 is the first which produces a branch, the lowest lateral 

 spike of the large, compoundly spicate inflorescence 

 arising on its axil. The small hypsophyllary leaves, 

 from the axils of which the individual flowers arise, em- 

 brace i or i. 



Valeriana officinalis. — The subterraneous runners ex- 

 hibit white, one-sidely apiculate, completely embracing, 

 cataphyllary-leaves, closed into tubes by the blending of 

 their borders. Of the alternating, two-ranked euphyllary- 

 leaves succeeding them, the lowest have likewise a com- 

 pletely embracing sheathing base, while the last embrace 

 only about |. The euphyllary-leaves found on the erect 

 part of the stem are connected in pairs, and embrace \, 

 or, on the triple whorls sometimes occurring, only \. The 

 hypsophyllary leaves have an arrangement similar to that 

 of the euphyllary leaves, but the two opposite leaves of 

 each pair do not quite reach one another with their bases ; 

 they are less than \, finally only \ embracing. 



Heracleum. — The loM'er and middle euphyllary leaves 

 of the species of this genus have overlapping sheaths, 

 therefore they reach somewhat more than completely 

 round the stem ; the upper, already smaller ones, having 

 a less divided and scarcely stalked lamina, usually approxi- 

 mated together, and having the umbel-bearing branches 

 in their axils, exhibit imperfectly embracing sheaths, 

 rapidly decreasing in breadth, about in the proportion 

 I. 5. I, h or falling still more quickly. Finally, the small 

 linear, or almost bristle-like hypsophyllary leaves of the 



