20 KEY TO THE SPECIES 



XVIII. NYCTAGINACEiE (Eour-o'clock Family) 



Herbs with entire fleshy opposite leaves, the stems with 

 swollen joints ; calyx corolla-like, its persistent base constricted 

 above the 1-celled, 1-seeded ovary and becoming an indurated 

 pericarp (anthocarp). 



1. ABRONIA (Abronia) 



Stems branching, more or less glandular ; peduncles axillary and terminal, 

 bearing a terminal involucrate cluster of several to many flowers ; periantb tube 

 elongated, with a 5-lobed limb. 



* Annual ; flowers small ; fruit with 3-4 broad wings. 



1. Abronia micrantha (Torr.) Chois. (Sand Flower). Prostrate, the ex- 

 tremities of the branches ascending ; leaves ovate to oblong, obtuse ; flowers 

 several, greenish-red or pink : the limb not more than 3-5 mm. broad ; wings of 

 the fruit 3 or 4, broad, membranous, wholly encircling the fruit, emarginate at 

 both ends, beautifully reticulated. 



* * Perennial ; flowers larger ; fruit with 2-5 narrow wings. 



2. Abronia fragrans Nutt. (White Abronia. Snowball). Stems several, 

 spreading, 3-7 dm. long, viscid-pubescent ; leaves ovate, obtuse, paired but differ- 

 ing in size ; peduncle long ; flowers numerous, white, forming a sub-spherical 

 cluster, opening at night and very fragrant ; fruit with narrow leathery wing, 

 which do not close over the summit. Common on sandy plains. 



XIX. PORTULACACEiE (Pueslane Family) 



Herbs with, entire fleshy leaves, conspicuous flowers that 

 open only in sunshine or bright daylight : sepals 2 (8 in Lewi- 

 sia), separate or united ; petals usually 5; stamens 3-many; 

 styles 2-8-parted ; capsule 1-celled. 



1. Portulaca. Flowers yellow ; stamens 7-20; capsule opening by a lid. 



2. I.ewisia. Flowers pink ; stamens numerous ; capsule globose, splitting 

 from the base upward, 



3. Claytonia. Flowers white, streaked with rose; stamens 3-5; capsule 

 splitting into 3 pieces. 



1. PORTULACA (Purslane) 



Low herbs, with scattered leaves, sessile flowers, 2-cleft calyx, 5 or 6 ephem- 

 eral petals, 7-12 stamens, a 5- or 6-parted style, and "a globular pod opening by 

 a lid. 



1. Portulaca oleracea L. ("Pcssley"). Prostrate and smooth; leaves 

 obovate or wedgef orm : petals pale yellow. Cultivated and waste ground. 



