CULTURE OF AQUATIC PLANTS. 
191 
Parkeria pteroides, named in honour of C. S. Parker, 
who first discovered this fern-like plant in Essequibo : its flowers 
are dark brown, in a short whorl; and although they are minute, 
yet its serrated pinnate leaves render it somewhat interesting. 
It succeeds well in loam and peat with the roots only immersed 
in water; it belongs to the natural order Polypodiacece. 
Hydrolea spinosa. This minute plant represents the 
order Hydrolacece ; and its flowers vie with the intense blue 
of the empyrean. The stem and foliage are decked with nu¬ 
merous spines, as a protection to the charming buds which raise 
their graceful form above them. It grows most luxuriantly in 
a loamy soil, in shallow water, and placed in a stove where heat 
is maintained. Its name is derived from hydor , water, elaia , 
oil. Introduced from South America in 1791. 
Victoria Regina. — This is the most difficult to procure, 
and most majestic in appearance: it flowers in January in its 
native country, Guiana. It was discovered by Sir R. H. Schom- 
burgk, in 1837 ; he describes it as “ a vegetable wonder.” Its 
immense leaves are from 6 to 7 feet in diameter, salver-shaped, 
with a broad rim of a light green above and vivid crimson 
below. Its flowers, resting upon the w r ater, are in character 
with its leaves, consisting of many hundred petals passing in 
alternate tints from pure white to rose and pink, about 15 
inches across. The leaf on its surface is bright green, in form 
orbiculate; the stem of the flower is an inch thick near the 
calyx, and is studded with sharp elastic prickles, about three 
quarters of an inch in length; the calyx is four-leaved, each 
leaf upwards of 7 inches in length, and three in breadth; they 
are thick and white inside, reddish brown and prickly outside; 
the diameter of the calyx is 12 or 13 inches. The magnificent 
flower, when fully developed, resting upon the calyx, completely 
covers it with its hundred petals ; when it first opens, it is 
white with pink in the centre, which spreads over the whole 
flower as it advances in age ; it is generally pink on the second 
day v after its expansion : as an enhancement of its remarkable 
beauty, it is also sweet-scented. 
Hardy and British Species. 
The aquatic plants which are cultivated in British aquariums 
possess considerable and peculiar attractions. The purple of 
Butomus umbellatiis gives an imposing effect to British ponds, 
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