240 BOTANICAL GAZETTE [march 



40:56. 1913. — Rulac texana Small, Fl. Southern U.S. 743 (in part). 

 1903. — This variety, the box elder of the Rocky Mountains, differs 

 from the variety texanum only in its narrower and usually more 

 acuminate and more irregularly serrate, often lobed leaflets usually 

 covered below with a closer pubescence, and in the more pubescent 

 or tomentose petioles and rachis. 



It ranges from Manitoba, Saskatchewan, and Alberta southward through 

 Wyoming, Montana, Colorado, Utah, New Mexico, and Arizona. The oldest 

 specimen of this tree which I have seen was collected by A. Fendler in New 

 Mexico in 1847 O^o- 102 in Herb. Gray). 



More distinct is the variety of Arizona and southern New Mexico, which 

 may be described as 



Acer Negundo var. arizonicum, n. var. — Leaves thin, 3- 

 foliolate; petioles slender, glabrous, 4.5-7 cm. in length, often 

 turning bright red late in summer; leaflets oblong-ovate to rhombic, 

 acuminate and long-pointed at apex, rounded or cuneate at base, 

 coarsely serrate, often slightly lobed near the middle, glabrous at 

 maturity with the exception of conspicuous tufts of axillary hairs, 

 6-10 cm. long and 3-5 cm. wide; petiolules slender, glabrous, 

 usually bright red, those of the terminal leaflet 2-2 . 5 cm. in length, 

 the others only 6-7 mm. long. Flowers not seen. Racemes of 

 fruit glabrous, 8-10 cm. in length; body of the fruit spreading, 

 glabrous, not constricted at the base. 



A tree 7-8 m. high with light gray fissured bark and slender glabrous 

 branchlets thickly covered with a glaucous bloom. 



Arizona. — Cave Creek Canyon, east slope Chiricahua Mountains, /. W. 

 Tourney, July 1894; Oak Creek Canyon near Flagstaff, Coconino County, 

 A. Rehder, July 14, 1914 (no. 34); Sycamore Canyon near Flagstaff, Percival 

 Lowell, October 191 5 and 1916; Santa Catalina Mountains, /. G. Lemmon, 

 May 1881 (no. 128 in Herb. Gray); Mount Kellogg, Santa Catalina Moun- 

 tains, altitude 2700 m., A. Rehder, August 31, 1916 (no. 463 type). 



New Mexico. — Kelley's Ranch, 7 miles north of Ahna, Socorro County, 

 A. Rehder, August 13, 1914 (nos. 279, 280; growing near no. 2S1, with densely 

 pubescent branchlets and leaflets pubescent below, and so referable to var. 

 interior); Glenwood, 7 miles south of Alma, Socorro County, A. Rehder, Au- 

 gust 14, 1914 (no. 300). 



This is the most glabrous of the forms of .4. Negundo, and in its thin leaflets, 

 bright red, petioles, and glabrous branchlets thickly covered with a glaucous 

 bloom one of the most distinct of them all. 



