26 THE AQUAVIVARIUM. 



the Aquavivarium ; as they grow up, however, 

 they need to be weeded out, and at last, as they 

 are annual, they will need removing. 



The AWL-WORT (Subula/ria aquatica), a little plant 

 with awl-shaped leaves and flowers which open 

 under water, has been recommended as a very 

 pretty addition to the Aquavivarian Flora. 



There is a little order of plants, called by Dr. 

 Lindley Hippurids (Haloragacece), all the 

 British species of which grow in water. The 

 most common of these is 



The SPIKED WATER MILFOIL (Myriophyllum spica- 

 tum), Fig. 2. It has flowers, with stamens and 

 pistils, which are arranged in whorls. The stem 

 is slender; the leaves are also arranged in a 

 whorl around the stem, and are four in number 

 in each whorl. There are several other species, 

 but this is the most common. 



MARESTAIL (Hippwris vulgaris) is another species 

 of plants belonging to this order. It is easily 

 known by its upright jointed stem, and the leaves 

 being in whorls of about eight round the stem. 

 It flourishes best in deep streams, and requires a 

 good deal of soil in order to prosper. 



VILLARSIA is the name given to a beautiful water- 

 plant, in compliment to Madame Villars, author 

 of the " Flora of Dauphine." This plant, of which 

 there is only one species in Great Britain, belongs 

 to the Gentian family (Oentianacece). This species 

 is so like the Water Lily that it is sometimes called 

 the little Water Lily ; and its Latin name ( Vil- 

 larsia nymphceoides) gives us the expression of 

 White Water-Lily-like Villarsia (Fig. 3). The 

 leaves are roundish, floating on the water ; the 

 flowers are large, and seated on single stalks, 

 and are of a beautiful yellow colour. It is 

 found in the Thames, and in some ponds in 



