133. LEMNACE.E. [1. Lemna. 



neuters below them. Anther-cells opening by vertical slits. Ovary 

 with many subbasal and parietal or orthotropous ovules. Fruit 

 membranous, few-seeded. Seeds albuminous, integuments strongly 

 thickened towards the micropj-le and forming a cap. Embryo ovate 

 or cuneiform, minute, apical. 



The seeds float and the first leaves of the seedling are roundish and lie ilat on tlie 

 water. 



1. P. stratiotes, L. 



Gregarious and resembling small floating cabbages with the obovate 

 leaves 1-3" long, rounded or retuse, nerves flabellate, raised beneath, 

 pubescent. Spathe pale yellow or white, -5" long, obliquely campanu- 

 late, contracted near the middle. 



In most districts ! Probably throughout the province but prefers the still back- 

 waters of rivers especially in districts with a Avarm winter. 

 Fl. h.s. Fr. c.s. 



FAM. 133. LEMNACEiE. 



Small or minute floating gregarious aquatics. Shoot {frond) not 

 differentiated into stem and leaf, sometimes also rootless and sub- 

 globose, usually explanate and distinctly dorsi-ventral ; sometimes 

 also, from the direction and branching of the weak vascular system, 

 a basal and apical portion is distinguishable. The branches grow 

 from the upper (dorsal) side of the frond, but are at an early period 

 enclosed in a pocket by the growth of the parent shoot and become 

 lateral, they may be soon detached and become independent plants. 

 Flowers most minute, monoecious, consisting of 1-2 naked stamens 

 in the male and naked 1 -celled ovary in the female, both male and 

 female sometimes enclosed in a common minute membranous spathe. 

 Stamens with 1-2-celled anthers. Ovary with short style and truncate 

 or funnel-shaped stigma. Ovules 1-7. Fruit a bottle-shaped utricle. 

 Seeds 1 or more with coriaceous testa, with or without albumen. 

 Embrj'o axile c^dindric. 



Fronds flat with 1 or more rootlets. Fls. sunk in marginal clefts. 



Anths. 2-celled " . . .1. L'mua. 



Fronds very minute, subglobose, rootless. Fls. dorsal. Auths. 



1-celled, sessile . ^ 2. Wulffia. 



1. LEMNA, L. Duck- weed. 



Fronds explanate with one or more very fine roots. ]M. and Fern. 

 fls. in marginal clefts enclosed together in a small transitory spathe. 

 Male of 2 stamens (or a pair of 1-stamened flowers ?) maturing one 

 after the other, with 2-celled (4-locellate when young) anthers and 

 slender filament, anthers dehiscing by transverse slits, pollen muricate. 

 Ovule orthotropous or half-anatropous. 



Note.— Engler separates from Lemna the genus Spirodela, Schleid. This is 

 distinguished by the daughter-shoot of the frond bearing at its base a small lobe 

 which is considered to be a basal leaf. Spii-odela has also several roots whereas 

 Lemna develops only one to each frond (or frond branch). In Spirodela is included 

 L. polijrrhiza and L. oligorrhiza. 



873 



