RKJUYENESCENCE 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, 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 |. 



Valeriana qfficinalis. 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 i, finally only \ embracing. 



Heracleum. The lower 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 

 1. ! !> ' or falling still more quickly. Finally, the small 

 linear, or almost bristle-like hypsophyllary leaves of the 



