Lemna. | LEMNACEA, 745 
1. LEMNA, Linn. 
Fronds proliferous from the sides near the base, with one or 
several delicate root-fibres descending from the under-surface. 
Flowers in marginal clefts of the fronds. Filaments slender ; 
anthers didymous, 2-celled; pollen globose, muricate. Ovary with 
1-7 ovules. Fruit a 1—-7-seeded utricle. Seeds erect or horizontal ; 
embryo conic or ovoid. 
A small genus of 8 or 9 species, most of them of almost worldwide distribu- 
tion. The two following are all that are positively known to occur in New 
Zealand, but others will probably be found. 
Root single. Fronds broadly ovate, thin, almost flat on 
both surfaces. Ovule solitary us WS Gaminon: 
Root single. Fronds broadly ovate, thick, conspicuously 
tumid beneath. Ovules2 .. x5 : .. 2. DL. gibba. 
1. L. minor, Linn. Sp. Plant. 970.—Root solitary, the sheath at 
its base without appendages. Frond symmetrical, }-+in. long, 
ovate or oblong, nearly flat on both surfaces, green above, paler 
beneath ; young ones growing from one side but soon becoming 
disconnected. Spathe unequally 2-lipped. Stamens 2, appearing 
successively (each a distinct male flower). Style rather long: 
Seed horizontal, hemi-anatropal, albuminous.—Hook. f. F'l. Nov. Zel. 
1. 239; Handb. N.Z. Fl. 278; Benth. Fl. Austral. vii. 163 ; Hegelm. 
Lemn. 141, t. 9, 10. 
NortH AND SoutH Isxanps: Still waters, abundant throughout. Sea- 
level to 2000 ft. Duckweed. Almost cosmopolitan in its distribution. 
2. L. gibba, Linn. Sp. Plant. 970.—Root solitary, the sheath at 
its base elongate, cylindric, rootcap acute. Frond symmetrical, 
+-+4 in. long, thick and spongy, flat above, convex beneath; young 
ones growing from one side, but soon separating. Spathe sac-like. 
Stamens 2. Ovules 2 or more. Utricle bursting transversely. 
Seeds erect, anatropous; albumen scanty or wanting.—Hook. f. 
fl. Nov. Zel. i. 239; Handb. N.Z. Fl. 278; Benth. Fl. Austral. 
vil. 163; Hegelm. Lemn. 145, t. 11-18. 
Nort Istanp: Poverty Bay, Colenso. 
I have seen no New Zealand specimens of this species, which is almost as 
widely distributed as L. minor. It is recognised at a glance by the conspicuously 
tumid under-surface of the frond. 
OrpER LXXXVIII. NAIADACEA. 
Submerged or floating fresh-water or marine aquatic plants, 
or marsh herbs. Stems often elongated, slender, branched, jointed; 
sometimes short and almost wanting. Leaves very various, alto- 
gether submerged and translucent, or floating and opaque, or all 
radical, sheathing at the base; stipules wanting or interpetiolar, 
