FLOWERING PLANTS AND FERXS OF ARIZONA 645 



7. APIASTRUM 



Plants annual, slender, glabrous; stems sometimes simple, usually 

 di- or tri-chotomously branching; leaves 2- or 3-ternate, the segments 

 subfiliform to linear; umbels compound, sessile in the axils or opposite 

 the upper leaves; involucre and involucel none; calyx teeth obsolete; 

 corolla white; stylopodium minute and depressed; fruit ovate or 

 cordate, 1 mm. long, papillate-roughened, the ribs inconspicuous, the 

 oil tubes solitary in the intervals, 2 on the commissure, the seed face 

 concave to sulcate. 



1. Apiastrum angustifolium Nutt. ex Torr. and Gray, Fl. Xorth 

 Amer. 1: 644. 1840. 

 Santa Rita Range Reserve and Coronado National Forest, Pima 

 County {Griffiths 429, 474, 516). Southern Arizona, California, and 

 Baja California. 



8. APIUM. Celery 



Plants annual or biennial, glabrous, branched above; leaves pinnate 

 to tenia te-pinnately decompound; umbels compound (or simple by 

 reduction), axillary and terminal, sessile to short-pedunculate; in- 

 volucre and involucel none; calyx teeth absent or inconspicuous; 

 corolla white; stylopodium short-conic; fruit ovate to suborbicular, 

 1 to 2 mm. long, laterally compressed, somewhat constricted at the 

 commissure, the ribs obtuse, conspicuous, the oil tubes solitary in the 

 intervals, 2 on the commissure, the seed face more or less plane. 



Key to the species 



1. Plant annual; leaves pinnately or ternate-pinnately decompound, the segments 



linear to filiform 1. A. leptophyllum. 



1. Plant biennial; leaves pinnate, the segments ovate to suborbicular or cuneate. 



2. A. GRAVEOLEXS. 



1. Apium leptophyllum (Pers.) F. Muell. in Benth., FL Austral. 3: 372. 



1866. 



Pimpinella leptophylla Pers., Syn. PL 1: 324. 1805. 

 Apium ammi (L.) Urban, Fl. Bras. 11 1 : 341. 1879. 



Tempe, Maricopa County, in a lawn {Stilt and McLellan in 1935). 

 Throughout North America. 



2. Apium graveolens L., Sp. PL 264. 1753. 



Havasu Canyon, Coconino County, abundant and apparently na- 

 turalized (Clover 4418), Maricopa County, at Phoenix (Dewey in 1891) 

 and Granite Reef (Gillespie 5626), Gila Indian Reservation, Pinal 

 County (Peebles 9652), in moist soil. 



Common celery, more or less naturalized throughout North America 

 from the Old World. 



9. SPERMOLEPIS 



Plants annual, caulescent, alternately branching, glabrous; leaves 

 ternately decompound, the segments filiform; peduncles axillary and 

 terminal, exceeding the leaves; umbels compound; involucre absent; 

 bractlets of the involucel few, filiform, shorter than the pedicels, 

 glabrous or callous-toothed; calyx teeth obsolete; corolla white; 

 stylopodium low-conic; fruit ovoid, 1.5 to 2 mm. long, laterally com- 

 pressed, covered with short echinate bristles, the oil tubes 1 to 3 in 

 the intervals, 2 on the commissure, the seed face more or less sulcate. 



