288 
The cultivation of this plant often presents no little difficulty 
owing to the tender net-like structure of its leaves. Water in which 
this plant is grown must not be above one-and-a-half feet deep, with 
a temperature not exceeding 75°- The y require a compost consisting 
largely of loan and decayed vegetable matter. This plant may be 
successfully grown in pots, placing them in large glass jars or glass- 
Aquaria having the desired depth of water, provided the water is 
renewed weekly. Partial shade. 
In Madagascar this is a valuable plant to the natives as the name 
implies (Ouvirandrano — literally Water-Yam or yam of the water). 
At certain seasons of the year, they gather it as an article of food, 
the fleshy root when cooked, yielding a farinaceous substance re- 
sembling a yam. 
O. fenestralis (window-leaved) The Lace-leaf or Lattice Plant. 
Flowers greenish white. The leaves are merely a network of vascular 
tissues resembling lace or a lattice window. 
Pistia, N.O. Aroideae ( Araceae ). A rapidly increasing stemless 
plant which often completely covers tropical ponds and watertanks, 
its chief beauty lying in the leaves, the flowers being inconspicuous. 
P. Stratiotes, Tropical Duckweed, Water Lettuce -—Flowers 
greenish, very small borne in little spathes at the end of the leaves, 
each spathe containing one male and one female flower attached to 
an adnate spadix. 
Leaves wedge-shaped, slightly concave, notched or round topped, 
of a delicate, pale pea-green, hispid, and connected together into a 
rose-shaped tuft. They send out runners bearing other plants in all 
stages of growth. As has already been mentioned in the Bulletin 
(Vol. page ) this plant forms a valuable fodder in the feeding 
of swine. 
The culture of this plant in tanks in artifically heated glass 
houses suffers occasionally from a fungus ; which completely disfigures 
the plant, many of the leaves turning yellow with occasional black 
blotches. 
Propagation.— This plant (as mentioned above) is of very easy 
propagation, i.e., by offsets. If grown for decorative purposes, it 
requires to be rather severely thinned out occasionally, and thrives 
luxuriantly in partial shade. The depth of water is immaterial, 
though larger rosettes of leaves are obtained if shallow water is used 
with a layer of rich soil at the bottom, the long, soft, feathery roots 
having ready access to it. 
Susum, N.O. Flagellarm, Aquatics or terrestial plants with 
creeping rhizome. Leaves closely crowded, ensiforme or lanceolate. 
Flowers small sessile green or yellow. 
