94 



NATURAL HISTORY OF PLANTS. 



All these plants have remarkable vegetative organs ; all are peren- 

 nial herbs, whose rootstock creeps in the mud of marshes or river 

 beds ; all have alternate leaves, more or less singular in form, some- 

 times dissected like the aquatic Crowfoots, as in Cabomba, in other 

 cases submerged or floating, palmate, sometimes peltate, and more or 

 less concave above, presenting the form of a very shallow cornet in 

 Nelumbium. In the Sarracenea, as mentioned above, this form 

 is exaggerated into a long, narrow cornet, whose apex forms a vari- 

 ably-lobed lid. The histology of the vegetative organs has been 

 most carefully studied by Trecul, 1 in Nelumbium, Nuphar, Nymphcea, 

 and Victoria, plants which in this point have often been regarded as 

 more or less comparable with Monocotyledons. 2 " In Nuphar luteal 

 says this botanist, " we find all the characters ascribed to the stem in 

 Monocotyledons. There are no distinct concentric layers, the pith 

 is interposed between the fibrous bundles, without medullary rays, 

 the density of the stem decreases from the circumference to the 

 centre. All this is shown in a transverse section ; it is seen that 

 the parenchyma, homogeneous in the centre, grows denser externally. 

 At a certain distance from the periphery are bundles, arranged more 

 or less regularly in a circle. In the centre are found some few 

 scattered bundles in a young stem, 3 the number increases with the 

 size of the rhizome. Outside the circular zone are other thinner 

 bundles going to the leaves. The whole is covered by a layer of 

 epidermic cells." The same general arrangement prevails in 

 Nympheeacea and Nelumbea. Trecul concludes from his observations 

 that "the structure of the rhizome in Nuphar is altogether that of the 

 Monocotyledons," as regards the longitudinal course of the bundles, 

 which behave as in the Date-palms, and springing from the circum- 



1 In Ann. Sc. Nat., ser. 3, iv. 288, t. 10-13; 

 Eiud. Anat. et Organogen. sur la Victoria regia, 

 et Anat. Comp. du Nelumbium, du Nuphar et 

 de la Victoria (in Ann, Sc. Nat., ser. 4, i 144, 

 t. 12-14). 



2 See Mikb., in Ann. Mus., xiii. 465. — Endl. 

 & Ung., Grundz. d. Bot., 92.— DC, in Mem. 

 Soc. Phys. de Gen., i. 2. — Hook. f. & Thoms., 

 Ft. Lid., i. 236.— Vaup., Ueb. d. Peripher. 

 Wachst. d. Gefassb. (1855), 23.— Henfr., in 

 Phil. Trans. (1852), 289, tab. ; in Ann. Nat. 



Hist., ser. 2, x. 398.— Casp., in Flora (1857), 

 717 ; (1859), 118 ; in Bot. Zeit. (1857), 791.— 

 Olit., Stem, in Dicot., 5. 



3 " At germination the tigellum of Nelumbium 

 codophyllum contains not a single central vascular 

 bundle, as in the young stages of Nuphar and 

 Victoria, but two zones of vascular bundles, one 

 central, one peripheral, above the insertion of the 

 cotyledons" (Tii£c., in Ann. Sc. Nat., ser. 4, i. 

 149, 169). 



