126 | - NAIDACEAE, [ Triglochin. 
high; raceme elongating after flowering. Flowers numerous, shortly 
pedicelled, minute, green or greenish-purple. Perianth-segments ovate, all 
equal. Stamens 6, all eae anthers purple. Fruit appressed to the 
thachis, linear-clavate, in. long; carpels 3, very slender, almost awned 
at the base, attached to the axis by the tip. —Cheesem. mn Trans. N.Z. yy nst. 
xiv (1882) 300; Man. N.Z. Fl. (1906) 747. eo, 
Soura Isnanp : Canterbury—Broken River, J. D. Enys and T. Ff. C. ; Tangiers 
Valley, Haast! Lake Tekapo and Tasman Valley, 7’. fF. C. Otago—Ophir, Black’s, 
Petrie ! 2000-3000 ft. December—January. 
A plant with a wide distribution in the Northern Hemisphere, also found in 
extratropical South America, but not yet detected in Australia. 
2. POTAMOGETON Linn. 
Perennial aquatic herbs. Stems slender, simple or branched. Leaves 
wholly submerged and translucent, or floating and opaque, alternate or 
opposite, entire or toothed ; stipules intrafoliar, free, or adnate to the 
petiole or base of the leaf. Flowers small, green, hermaphrodite, ebracteate, 
sessile in a dense spike on an axillary peduncle arising from a membranous 
spathe. Perianth-segments 4, small, herbaceous, concave, valvate. Sta- 
mens 4, inserted at the base of the segments; anthers sessile, 2-celled, 
extrorse. Carpels 4, sessile, distinct, l-celled; stigma oblique, decurrent ; 
ovules solitary, affixed to the inner angle of the cell, campylotropous. 
Ripe carpels or drupelets 4, small, coriaceous or spongy, ovoid or sub- 
globose, obtuse or beaked by the recurved persistent stigma, 1-seeded. 
Seed curved, reniform; testa membranous; embryo with a large radicle 
and narrow incurved cotyledon. 
A genus widely spread in the fresh or brackish waters of almost all temperate or 
subtropical regions, more rare in the tropics. Species variously estimated at from 
40 to 100 or more, according to the different views of authors, extremely variable, 
and most difficult of discrimination. The New Zealand forms have never been carefully 
sought for, and in all probability other species will be added to those described 
herein. 
A. Floating leaves more or less coriaceous, with a broad long-petioled lamina, different in 
shape from the membranous submerged ones. Stipules free. 
Floating leaves 2-4 in., biplicate at the base. Submerged leaves 
wanting or reduced to phyllodes. Fruit large, }in. long, 
keeled on the back when dry : + os ft P. natans. 
Floating leaves 1-3in., not plicate at the ‘base. Submerged 
leaves few, linear-lanceolate. Fruit small, 4—,in., rounded 
on the back rai * ¥ ‘f a , Ppolygonifolius,) “ 
Floating leaves 3-l?in. Submerged leaves numerous, 2-4 in. Nan 
Fruit small, ;4, in., keeled on the back when dry ee t ecabioteg Biter 
wS 
: : LE. mean Wrane*® hi 
B. Leaves all Bed and uniform, sessile, membranous. ” ‘ ‘ 
Leaves 1-4in, by 4 Sepia Saas obtuse ; stipules free,~ ~ he algal > iaiong 
lacerate. eee dense of .. 4. P. ochreatus. 
Leaves 2-4 in. by 3,-;4 in., very narrow- linear or filiform ; ; stipules 
adnate. Spike interrupted oF oe ne .. 5, P. pectinatus. 
1. P. natans Linn. Sp. Plant. (1753) 126.—Stems creeping below, long 
or short, simple or sparingly branched, terete. Floating leaves on long 
petioles; lamina 2-4in. long, oblong or elliptic or elliptic-lanceolate, 
acute or subacute, subcordate and shortly biplicate at the base, coriaceous, 
20-30-nerved with copious cross-veins and minute areolation ; stipules 
very long and conspicuous, 3-5in., free, acuminate. Submerged leaves 
