



ULMACE^: 287 



tomentose in their first winter, ultimately glabrous and dark red-brown or black; 

 sometimes 60-70 high, with a trunk 4-5 in diameter, with a head occasionally 

 100 across; or at high elevations or on exposed mountain slopes a low shrub. 

 Winter-buds oval, acute, about -J' long, pale pubescent toward the apex, with thin 

 closely imbricated light chestnut-brown ciliate scales. Bark l'-2' thick, dark brown 

 or nearly black, deeply divided into large oblong thick plates separating into small 

 thin closely appressed scales. Wood heavy, strong, brittle, close-grained, dark 

 brown or almost black, with thick bright brown sapwood tinged with red. The 

 sweet acorns are an important article of food for Mexicans and Indians, and are sold 

 in the towns of southern Arizona and northern Mexico. 



Distribution. Mountain ranges of western Texas, southern New Mexico and 

 Arizona south of the Colorado plateau, and of northern Mexico; in Texas common 

 in the canons and on the southern slopes of the Limpio and Chisos mountains; the 

 most abundant Oak of southern New Mexico and Arizona, forming a large part of 

 the forests covering the mountain slopes and extending from the upper limits of the 

 mesas nearly to the highest ridges; attaining its largest size and beauty in the 

 moist soil of sheltered cafions. 



Section 2. Flowers unisexual (usually perfect in Ulmus) ; 

 calyx regular ; stamens as many as its lobes and opposite them ; 

 ovary superior, 1-celled (rarely ^-celled in Ulmus} ; seed 1. 



XI. ULMACE-53. 



Trees, with watery juice, scaly buds, terete branchlets prolonged by an upper 

 lateral bud, and alternate simple serrate pinnately veined deciduous stalked 

 2-ranked leaves unequal and often oblique at the base, conduplicate in the bud, 

 their stipules usually fugaceous. Flowers perfect or monoeciously polygamous, 

 clustered, or the pistillate sometimes solitary ; calyx 4-9-parted or lobed ; 

 stamens 4-6 ; filaments straight ; anthers introrse, 2-celled, opening longitudi- 

 nally ; ovary usually 1-celled ; ovule solitary, suspended from the apex of the 

 cell, anatropous or amphitropous ; styles 2. Fruit a samara, nut, or drupe ; 

 albumen little or none ; embryo straight or curved ; cotyledons usually flat or 

 conduplicate. Five of the thirteen genera of the Elm family occur in North 

 America. Of these three are represented by trees. 



CONSPECTUS OF THE NORTH AMERICAN ARBORESCENT GENERA. 



Fruit a samara ; flowers perfect. 1. Ulmus. 



Fruit nut-like, tuberculate. 2. Planera. 



Fruit a drupe ; pistillate flowers usually solitary. 3. Celtis. 



1. ULMUS, L. Elm. 



Trees, or rarely shrubs, with deeply furrowed bark, branchlets often furnished 

 with corky wings, and buds with numerous ovate rounded chestnut-brown scales 

 closely imbricated in two ranks, increasing in size from without inward, the outer 

 sterile, the inner accrescent, replacing the stipules of the first leaves, deciduous, 

 marking the base of the branchlet witli persistent ring-like scars. Leaves simply or 

 doubly serrate; stipules linear, lanceolate to obovate, entire, free or connate at the 



