Excerpta Botanica. 261 



andri. Filamenta filiformia. Anthera biloculares, loculis sub- 

 globosis, apice contiguis, basi remotissimis, bilocellatis, rima 

 longitudinal! laterali dehiscentibus. Pollen globosum, murica- 

 tum, rima unica (?) donatum. Foom. 1. Ovarium uniloculars 

 uni- multi- (septem- in L. gibba) ovulatum. Ovulum anatro- 

 pum vel hemianatropum vel atropum, in tegumentis binis. Sty- 

 lus continuus ; stigma expanso-infundibuliforme. Fructus : utri- 

 culus mono-polyspermus, indehiscens vel capsula circumscissa. 

 Semen in tegumentis binis, externo coriaceo-carnoso, interno 

 membranaceo ; endostomio indurato (operculo) in germinatione 

 embryostega. Embryo in axi albuminis carnosi rectus, mono- 

 cotyledoneus, gemmula seorsim (radiculam) spectans in rima 

 laterali, radicula supera, infera vel vaga*. 



f Vasa spiralia transitoria, vel nulla. Plantce novella? nudee. 



A. Frondes rima una basilari hiantes. Flores in pagina frondis superior e 



erumpentes. 



I. Wolffia, Horkel MSS. (Horkelia, Reich, non Schlechtend.) 



Flos masculus unicus. Filamentum breve, crassiusculum. Flosfoemi- 

 neus unicus. Ovarium uniloculars uniovulatum, ovulo uno 

 recto, anatropo ; stylus brevis ; fructus utriculus monospermus ; 

 semen erectum ; embryo turbinatus ; radicula supera. 



1. W. Delilii. Frondes ovales, tenuissimse, geminatim opposite, 

 arrhizse ; labium inferius rimse basilaris productum, appensum, 

 hyalinum. Lemna hyalina, Del. Lemna e Rosetta, Herb. Willd. 

 no. 17144. L. arhiza, Herb. Willd. 17141. 



The author is indebted to Dr. Ehrenberg for specimens of Wolffia 

 in flower brought from Egypt ; and he detected in Willdenow's her- 

 barium specimens of the same plant in fruit, under the name of 

 Lemna, from Rosetta. 



B. Frondes rimis binis basilaribus hiantes. Flores e rima later aliter pro- 



deuntes. 



II. Lemna. 



Flores masculi, altero in evolutione prsecociori. Filamenta filiformia, 

 recurva ; ovarium uniloculars uniovulatum, ovulo erecto, hori- 

 zontal!, hemianatropo ; stylus elongatus, recurvus ; fructus 

 utriculus monospermus indehiscens ; semen in fundo affixum , 

 horizontale ; embryo conicus ; radicula vaga. 



1. L. minor, Linn. Frondes obovato-subrotundae, crassiusculae, 

 ternatim quaternatimque, rarius plures cohserentes, monorrhizse ; 

 stipite frondis novelise discreto fragili. L. cyclostasa, Ell. L. 

 minuta, Kunth. L. minima, Chev. L. conjugata, Willd. Herb. 

 17143. 



* Brongniart's description of the embryo in ' Archives de Botanique ' is 

 very far from being accordant with nature, nor can I possibly imagine what 

 could lead him to the supposition of a canal pervading the upper portion of 

 the embryo and nourishing a cordate plumule at its base. 



