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DOMESTIC BOTANY. 



with leaves like chickweed, arranged three in a whorl, on 

 long, slender, floating stems, which are densely matted 

 together. It is a native of N. America, and about 20 years 

 ago made its appearance in this country, spreading so rapidly 

 that it was feared it would choke up the canals and so pre- 

 vent navigation. It, however, forms such dense masses that 

 it ultimately becomes exhausted and dies out. 



Grass- wrack {Zostera marina). A plant with long, narrow, 

 tape-like leaves, 3 — 4 feet in length. It is a native of this 

 country, being generally found in the estuaries of tidal rivers. 

 When dried it is used for packing, stuffing beds, cushions, 

 &c., and is known by the name of Alva marina. 



The Duck-Weed Family. 



(LEMNACEiE.) 



Small stemless plants, loosely floating on the surface of 

 ponds and stagnant pools in this country. They consist of 

 simple or lobed leaves, and bear small inconspicuous flowers. 

 There are about 20 species, widely distributed in Jamaica and 

 other tropical countries. Pistia stratiotes is a singular plant 

 with bright green wedge-shaped leaves, growing in a rosulate 

 manner. It is said to putrify the water, causing miasma. Its 

 curious mode of floating and propagating may be seen in the 

 aquariums at Kew. 



THE ARUM, SCEEW PINE, AND PALM ALLIANCES. 

 The Arum Family. 



(Aroide^) 



Palmids, phyllacorms, epiphytal ampelids, orrhizocorm 

 herbs, gecerally of a soft texture, destitute of pubescence. 

 Leaves with sheathing petioles ; entire, digitate, or va- 

 riously lobed, either membranous or leathery, and with 

 netted veins. Inflorescence enclosed in a spathe, consist- 

 ing of a compact fleshy spike (spadix), of small sessile 



