18 



MEMOIRS FKOM THE DEPARTMENT OF BOTANY OF COLUMBIA COLLEGE. 



or sul)ulate, persistent, more or less dilated at the base, and sometimes alternating with 

 small scales ; anthers varying from oblong to ovoid, dehiscing longitudinally, attached 

 about the middle of the back. Ovary lenticular or triquetrous; ovule usually stipitate; 

 style two or three-cleft or two or three-parted, sometimes wanting; stigmas two or three, 

 capitate, rarely one, and sessile and more or less two or three-cleft. Achene lenticular or 

 triquetrous, membranous or coriaceous, included in the persistent calyx or more or less 

 exserted, smooth or granular, the angles rounded or sharp, the faces more or less concave 

 or con\'ex. Seed sessile, albuminous, usually of the same shape as the achene, with a 

 broad hilum at the base. Albumen horny or mealy. Embryo situated in one of the 

 angles of the albumen. Cotyledons foliaceous, slender, accumbent or incumbent. 



KEY TO THE SUBGENERA. 



Alpine or subalpine plants, perennial by a bulb-like, creeping or horizontal root- 

 stock; leaves radical and cauline ; ocreae membranous, cylindric, naked, opened 

 obliquely at the summit ; inflorescence consisting of a single terminal spicate raceme ; 

 flowers subtended by usuallj^ toothed bract-like ocreolae ; calyx five-parted ; stamens 

 var3'ing from five to eight ; style three-parted, exserted ; achene triquetrous ; cotyle- 

 dons accumbent. ^ 1. Bistoriia. 



Alpine or sub-alpine plants, perennial by more or less elongated creeping or 

 horizontal rootstocks ; leaves cauline, somewhat fleshy or coriaceous ; ocreae funnel- 

 form, membranous, oblique, naked; inflorescence consisting of terminal clusters, 

 racemes op paniculate racemes ; flowers subtended by ocreolae ; calyx five-parted, 

 stamens eight ; style three-cleft ; achene triquetrous ; cotyledons accumbent. 2. Aconogonon. 



Herbaceous or more or less wood\', annual or perennial plants ; leaves all cau- 

 line ; ocreae mostly membranous, cylindric, truncate, naked or variously fringed ; 

 inflorescence consisting of terminal, spicate racemes, usually geminate or pani- 

 culate ; flowers subtended by ocreolae ; calyx varying from three-parted to five- 

 parted ; stamens varying from four to eight ; style two-parted or three-parted, or two- 

 cleft or three-cleft, included or exserted ; achene lenticular or triquetrous ; cotyledons 

 accumbent. 3. Persicarta. 



Large annual plants (with the habit of Persicaria) ; leaves cauline ; ocreae mem- 

 branous, cylindric, truncate, with a more or less spreading summit, fringed with bris- 

 tles ; inflorescence consisting of terminal spicate racemes, more or less paniculate ; 

 flowers subtended by ocreolae ; calyx five-parted ; stamens mostly seven, varying 

 from five to eight ; style two-cleft ; achene lenticular ; cotyledons incumbent. 4. Amblygonon. 



Annual herbaceous plants ; leaves cauline, mostly ovate or elliptic-ovate ; ocreae 

 membranous, cylindric, fringed with bristles; inflorescence consisting of axillary and 

 terminal much interrupted spicate racemes ; flowers subtended by ocreolae ; calyx 

 unequally four-parted ; stamens flve ; style two-parted, exserted ; achene lenticular, 

 cotyledons accumbent. 5. Tovara. 



