CLASS IV. ORDER iii.J POTAMOGETON. 207 



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Below a circling fence, its leaves are seen 



Wrinkled and keen ; 



No grazing cattle through (heir prickly round 



Can reach to wound; 



But, as they grow where nothing is to fear, 



Smooth and unarm "d the pointless leaves appear, 



Vario\is reasons are given by authors as to the origin of decorating- 

 chnrches and dwelling-houses with the branches of Holly during the 

 Christmas festival, but nothing appears to be known with certainty as 

 to its origin, beyond that of its great antiquity. Dr. Chandler supposes 

 this custom to be derived from the Druids, who, he says, decorated 

 their dwelling-places with evergreens during winter, " that the sylvan 

 spirits might repair thither, and remain unnipped by frost and cold 

 winds, until a milder season had renewed the foliage of their darling 

 abodes." — " The Holly {Creil Thionn, in Gaelic) is the badge of the 

 clan Drumjnond." 



GENUS XIX. POTAMO'GETON. Linn. Pondweed. 



Nat. Ord. Fluvia'les. 



Gen. Char. Flowers in spikes, arising from a sheathing hractea, or 

 spatha. Perianth single, of four pieces. Stmnens, with the 

 anthers, nearly sessile, opposite the pieces of the perianth. Pistils 

 four, alternating with the stamens, becoming compressed. Nuts 

 each containing a suspended, curved, more or less spiral seed. — 

 Name from Trora.jj.o';, a river, and yuruv, a neighbour ; on account 

 of the species all growing in water. 



* Leaves all opposite ; stipules none. 



1. P. den'sus,\jmn. (Fig. 264.) opposite-leaved Pondweed. Leaves 

 opposite, embracing the stem, crowded. 



English Botany, t. 397.— English Flora, vol. i. p. 231.— Lindley, 

 Synopsis, p. 248. — Hooker, British Flora, vol. i. p. 75. 



Roots fibrous, arising from the lower joints of the long creeping 

 stems. Stem naked below, forked and thickly clothed above with 

 opposite, ovate, acuminate or lanceolate, sessile, spreading leaves, em- 

 bracing the stem, recurred, having a strongish midrib formed of nu- 

 merous longitudinal cells, and two or three lateral parallel veins united 

 by distant fibres, the margins waved, entire. Inflorescence a small 

 round spike of about four green flowers, on a short round stalk, erect 

 when in flower, recurved in seed. " The head is just out of the water 

 during impregnation, after which, by the increase of the branches, it 

 sinks, and ripens the seed, whilst other flowers come forth above. The 

 deeper the water, the larger is the whole plant." 



