ROSACEAE
The Haws, Thorns, Hawthorns or Thorn-apples
Crataegus L.
Owing to the complexity of the various forms in this group, the present state of uncertainty as to the value of certain characters, and the questionable validity of many of the assigned names, it is thought to be beyond the scope of this bulletin to give more than a general description of the group as a whole, recommending the more ambitious student to the various manuals and botanical journals and papers for more detailed information.
The Crataegi are generally low, wide-spreading trees or shrubs, with strong, tortuous branches and more or less zigzag branchlets usually armed with stiff, sharp thorns. The bark varies from dark red to gray and is shallowly fissured or scaly. The leaves are alternate, simple, generally serrate, often lobed, with short or long petioles. The flowers appear in May or June, with or after the leaves, in simple or compound corymbs, whitish or pinkish, perfect. The fruit is a red to yellow, sometimes blue or black pome, subglobose to pear-shaped, with usually dry and mealy flesh and 1-5 seeds. The winter-buds are small, nearly globose, lustrous brown. Crataegus produces wood which is heavy, hard, tough, close-grained, red-brown, with thick, pale sapwood. The Haws are trees of the pasture-lands, the roadside, the open woods and the stream-banks, and are more common in the southern than in the northern portions of the state. Some of the species are desirable as ornaments in parks and gardens on account of their beautiful and abundant flowers and showy fruits.
SUMMER KEY TO THE SPECIES OF PRUNUS
| a. | Leaves oblong-ovate to obovate, abruptly acuminate at theapex; marginal teeth not incurved. | ||
| b. | Margin of leaves sharp-serrate with spreading teeth;leaves not rugose, the veins not prominent; fruit 1/4-1/2inch long, bright red, racemose, July-August; bark oftrunk brown, smooth or only slightly fissured; usually alarge shrub. | P. virginiana, p. [157]. | |
| bb. | Margin of leaves crenate-serrate; leaves more or lessrugose, the veins prominent; fruit about 1 inch longorange-red, clustered, August-September; bark of trunkgray-brown, early splitting off in large, thick plates;a small tree. | P. nigra, p. [161]. | |
| aa. | Leaves oval to oblong-lanceolate, taper-pointed at the apex;marginal teeth incurved. | ||
| b. | Fruit light red, clustered, July-August; twigs usually lessthan 1/16 inch thick; pith of twigs brown; tree northern. | P. pennsylvanica, p. [139]. | |
| bb. | Fruit black, racemose, August-September; twigs usuallymore than 1/16 inch thick; pith of twigs white; treesouthern. | P. serotina, p. [155]. | |