174 COXTKIBUTIONS FROM THE NATIONAL HERBAEIUM. 



the deciduous-leaved species, being frequently more than 10 cm. long and half as 

 broad. They are of a rich dark green and glabrous on the upper surface and much 

 paler beneath. In outline the leaves are broadly elliptic-obovate, deeply pinnate- 

 lobed, the rounded, open sinuses reaching three-fourths the way to the midrib. The 

 lobes are broadly oblong to triangular, rounded toward the acute or obtuse apex, and 

 many of them bilobate. The acorns are large, with hemispheric cups having mod- 

 erately thickened scales. 



A queer form which seems to be most nearly related to this species is shown in 

 Standley's 4755 from Winsors Ranch, where it is common on rich hillsides. The 

 leaves are divided to within 2 or 3 mm. of the midrib, the segments reduced in num- 

 ber and size; in a few cases the leaf is reduced to a long-ob lanceolate form less than 1 

 cm. wide at the obtuse tip, without lobes of any kind. 



24. Quercus gambelii Xutt. Journ. Acad. Phila. II. 1: 179. 1848. Gambel oak. 



Quercus douglasii gambelii A. DC. in DC. Prodr. 16^: 23. 1864, in part. 



Quercus undulata gambelii Engelm. Trans. Acad. St. Louis 3: 382. 1876. 



Type locality: Banks of the Rio Grande, New Mexico, west of Santa Fe. Type 

 collected by Gambel. 



Range: Mountains of northern New Mexico and southern Colorado. 



New Mexico: Chama; Tierra Amarilla; Canjilon; Santa Fe and Las Vegas moun- 

 tains; Johnsons Mesa; Sandia Mountains; Zuni Mountains; East View. At middle 

 elevations, in the Upper Sonoran and Transition zones. 



The original description of this species applies to a shrubby, deciduous, green- 

 leaved oak with an acute acorn, from the region of Santa Fe. Such an oak is to be 

 found in that region, although it is by no means the common form. Most of the de- 

 ciduous, green-leaved oaks of New Mexico and Colorado have obtuse or truncate 

 acorns, and are to be found listed here under other names. If one were to consider 

 all the white oaks of the State as belonging to a single species, it should be called Q. 

 gambelii; but there are numerous easily recognizable variants of that type and our 

 judgment as to their proper recognition is expressed in this treatment. 



Order 20. URTICALES. 



KEY TO THE FAMILIES. 



Fruit a samara or drupe, sometimes nutlike 34. TJLMACEAE (p. 174). 



Fruit an achene. 



Flowers on the outside or inside of a recej^ta- 

 cle; fruits forming syncarps; sepals ac- 

 crescent, enveloping the achenes 35. MORACEAE (p. 175). 



Flowers not on a receptacle; fruits not forming 

 syncarps; sepals neither thick and juicy 

 nor enveloping the achenes. 

 Style or stigma 1; ovule erect; filaments 



inflexed in the bud 36. URTICACEAE (p. 176). 



Styles or stigmas 2; ovule pendulous; fila- 

 ments erect in bud 37. CANNABINACEAE (p. 177). 



34. TJLMACEAE. Elm Family. 



1. CELTIS L. Hackberry. 



A small tree or large shrub; leaves ovate or ovate-lanceolate, abruptly acuminate, 

 reticulate, cordate and very unequal at the base; flowers greenish, axillary, the 

 fertile solitary or in pairs, appearing with leaves; calyx 5 or 6-parted, persistent; 

 stamens 5 or 6; ovary 1-celled, with a single ovule. 



