S/jarganium ,~\ 
V. TYPHACBjE. 
277 
surrounded by a perianth of 3-6, small linear scales. Nuts ovoid or ob- 
ovoid, thick. 
A small aquatic genus, found in all temperate climates. 
1. S. simplex, Hurls. ; — FI. N. Z. i. 238. An erect, rather flaccid 
herb, 1-2 ft. high. Leaves a foot long, in. broad, acute, channelled. Scape 
slender, erect, not branched. Nuts broadly obovoid, £ in. long, suddenly 
contracted into a slender style. 
Northern Island: in watery places frequent, Tiidwill, etc. “Simple Bur-reed” of England, 
a common plant in various parts of the New aud Old World, including Australia, but not 
found in Tasmania. 
Order VI. NAIADEiE. 
Floating, submerged, or erect marsh plants (in Lenina reduced to floating 
green scale-like fronds). Leaves alternate, linear or oblong, sheathing at the 
base. Stipules usually interpetiolar, membranous, sheathing. Inflorescence 
various, usually spiked. — Flowers minute, green, inconspicuous, unisexual or 
hermaphrodite. Perianth inferior, regular, of 4-6 green pieces in 2 series, or 0, 
or reduced to scales, or to a tubular sheath. Stamens 1, 4 or 6; filaments 
usually short ; anthers 2- or 4-celled, inserted by their base, dehiscing longi- 
tudinally ; pollen often of confervoid threads. Ovaries free, 1-6; styles 
short or long, stigmatiferous on the inner face; ovule 1, usually pendulous 
in each cell. Fruit of 1-6 indehiscent nuts, rarely drupes or capsules. 
Seed erect or pendulous, albumen 0 ; testa membranous ; embryo with a very 
large radicle, usually curved or indexed ; plumule in a slit on one side of it. 
Au extensive family of water plants, scattered over the whole globe. 
Small scale-like floating fronds 1. Lemna. 
Simple or branched marsh or water plants. Leaves linear or oblong. 
Flowers spiked. 
Perianth 6-leaved. Stamens 6 ; anthers subsessile ..... 2. Trtgi.ochin. 
Perianth 4-leaved. Stamens 4 ; anthers subsessile 3. Potamogeton. 
Perianth 0. Stamens 4 ; anthers sessile. Ovaries 4. Nuts on long 
stalks 4. Ruppia. 
Flowersaxillary. Male fi. : a long stamen. Female: 2-5 ovaries in a 
sheathing perianth 5. Zannichei.ua. 
1. LEMNA, Linn. 
Minute green scale-like fronds, covering the surface of ponds and ditches. 
Eoots thread-like, suspended from the frond. Flowers most minute, appearing 
by threes in a cleft of the frond, surrounded by a thin membranous spathe. — 
Two of the flowers are males and consist of a single stamen each, with slender 
filament and 2-celled anther; the other is a female, and is a 1-celled I- or 
2-ovuled ovary, with a funnel-shaped stigma. Fruit a most minute 1-4- 
seeded utricle. Seed erect or horizontal ; testa ribbed, membranous ; albu- 
men 0 ; cotyledon thick, farinaceous, including the radicle and plumule. 
A genus of few species, scattered over the globe, rarely found in flower. “ Duckweed.” 
Frond oblong or oval, flat below . . 1. L. minor. 
Frond oblong or oval, convex below . . . 2. L. gibba. 
