Prof. Sargent has examined and named all of my material for me. Mr. B. F. 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 by Sargent and Bush, and am following the nomenclature of the first edition, I regard the present treatment as tentative only.
| Margins of all the leaves sharply serrate all around except at base; nutlets 6-8 mm. long | [1 C. occidentalis.] |
| Margins 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 5-6 mm. long. | |
| Leaves of a rather broad ovate type; mature fruit a dark cherry-red; usually shrubs, sometimes very small trees, of a dry habitat | [2 C. pumila.] |
| Leaves of an ovate-lanceolate type; mature fruit a light cherry-red; medium-sized trees of a wet habitat | [3 C. mississippiensis.] |
CELTIS OCCIDENTALIS Linnæus. Hackberry. (x 1/2.)
1. Celtis occidentàlis Linnæus. Hackberry. [Plate 61.] Medium to large-sized trees; bark of old trees irregularly furrowed, sometimes some of the surface warty and rough; twigs smooth or pubescent, the fruiting ones generally smooth; leaves of an ovate type on petioles 0.5-2 cm. long, the blades of fruiting twigs 5-15 cm. long, those of vegetative twigs sometimes larger, oblique or slightly cordate at base, gradually tapering to a point at apex, or long acuminate at the apex, often becoming thick at maturity, especially those exposed to full sunlight, generally smooth above at maturity, especially those of fruiting twigs, or sometimes rough, especially those of vegetative branchlets or those growing in the shade, the under surface more or less pubescent along the veins at maturity; fruit matures in late autumn, very dark red, sometimes appearing almost black, globose or somewhat oblong, generally about 9-10 mm. in diameter, borne on pedicels which are longer or up to twice as long as the petioles; the pedicels which are always ascending are straight or somewhat curved upwards; nutlets globose, a little longer than wide.
Distribution.—Valley of the St. Lawrence River, southern Ontario, to North Dakota, and south to the Gulf States and west to Texas. More or less frequent along streams throughout the State, except in the hilly counties of the southern part of the State. It is always found in moist soil, except in the hilly counties where it may be found on wooded slopes or on high rocky bluffs bordering streams. In all of our area the species is practically confined to drainage basins, and is generally close to streams.