146 



2. CELTIS. The Hackberries. 



Trees with pith of branehlets chambered ; flowers m Indiana species 

 appear before the leaves, tlie leaves generally with 3 primary veins at the 

 base; staminate flowers usually in clustei's, the pistillate solitary or 

 few together in the axils of the leaves, and near the end of the twigs; 

 fruit a globose drupe, sometimes elongated, pulp thin and sweet, fre- 

 quently remaining on the tree until late winter, relished by birds; stone 

 bony, wrinkletl. 



Some of the American species of hackberry are very variable. The 

 haliitat of the species varies from deep swamps to arid rocky slojaes. In 

 fact, a single species as now understood may have a variable habitat. 

 The following variations may be noted on the same tree or on different 

 trees of the same species. The twigs may be glabrous, or pubescent; 

 the leaves may vai'.y in size, shape and texture, leaf margin, ami in the 

 roughness or smoothness of the surfaces; the jaetioles may be smooth 

 or hairy; the pedicels may be glabrous or pubescent, shorter or longer 

 than the petioles; the fruit also varies in shape. Leaves have been seen 

 on the same tree which were smooth above, while others were quite 

 rough above, the difference being due to the exposure to light. 



The original descriptions of the species are too short to sufficiently 

 characterize the sjiecies, which adds to the confusion. However, C. S. 

 Sargent' has recently revised the species and varieties of our area. 



Prof. Sargent has examined and named all of my material for me. 

 Mr. B. r. Bush, who has extensively studied the hackberries in the 

 field, also has examined my specimens. 



The writer has paid special attention to the hackberries of the State 

 for the past few years and is still in doubt as to the status of the species 

 that occur in the State. Since I am not following the determinations 

 made Ijj' Sargent and Bush, and am following the nomenclature of the 

 first edition, I regard the present treatment as tentative onljr. 



Mar^in.'^ of all the leaves sharply serrate all around except at 



liase; mitlets 6-8 mm. long 1 C. occiden talis. 



JNIargins of leaves of fruiting branches generally entire, or 

 some with a few teeth on one side or with a few teeth on 

 both sides; margins of the leaves of vegetative branches 

 and shoots similar to those of fruiting branches or with 

 the margins serrate nearly all around ; nutlets .5-0 mm. long. 

 Lea^'cs of a rather broad ovate type; mature fruit a dark 

 cherry-red; usually shrubs, sometimes very small trees, 



of a dry habitat 2 0. pumila. 



Lea\'es of an ovate-lanceolate type; mature fruit a light 



cherry-red; medium-sized trees of a wet habitat S O. mississippi- 



ensis. 



iBot. Claz. Vol. 07:217-229:1919. 



