From Flora of Indiana (1940) by Charles C. Deam

Leaves ovate, rhombicovate or suborbicular, mostly 2.5-6 cm long, 2-5 cm wide, rounded or abruptly pointed at the apex, abruptly narrowed, rounded or truncate at the base, sharply serrate nearly to the base, usually with 3 or 4 pairs of shallow, obscure or rounded lateral lobes, firm to subcoriaceous at maturity, scabrate above and more or less villous on the veins beneath while young, becoming glabrate or remaining slightly villous beneath; petioles slender, a third to half the length of the blades, somewhat villous or tomentose; flowers 14-17 mm in diameter, in compact, compound, villous or thinly tomentose, mostly 5-10-flowered corymbs; stamens about 20; anthers white or tinged with pink; fruit subglobose or short-ovoid, 14-20 mm in diameter, bright yellow (according to description) or red, punctate, with a slight bloom; nutlets usually 5. A tree up to 6-7 m high, with dark, rough, deeply furrowed bark, and ascending or wide-spreading branches, forming a low, conical crown ; branchlets slender, unarmed or sparingly armed with stoutish or slender purple thorns. Known in Indiana only from Wells County where a tree was found in a clearing on the land of the Erie Stone Company about 2 miles northwest of Bluffton. Crataegus Kelloggii is probably a hybrid between Crataegus Margaretta and Crataegus mollis, and may be looked for where those two species are found together. There is much variation in the characters of the fruit, foliage, and flowers, as is to be expected in hybrids. The fruit of the type tree was described as bright yellow, an unusual color in the genus and probably exceptional in this species, although it is interesting to note that a yellow-fruited form of both parent species has been found. Crataegus mollis appears to hybridize with other species. It has been suggested that Crataegus platycarpa may be a hybrid between this and some species of the Pruinosae group (possibly Crataegus rugosa), and forms have been found in Lawrence County that appear to be hybrids between Crataegus mollis and Crataegus pruinosa, and possibly also between Crataegus mollis and Crataegus punctata.