One of several Viburnum species found in our area; this one is not recorded in the literature as occurring in Allegheny County, though it is known to occur in neighboring Butler County. (Shafer’s Preliminary List of the Vascular Flora of Allegheny County, Pennsylvania, lists it as a possible resident, on the grounds that it occurs in neighboring areas.) Nevertheless, these bushes seem to be Viburnum dentatum, and they did grow in Allegheny County, near the edge of the woods on the grounds of Harmarville Rehabilitation Hospital. (We’d be delighted to be corrected in this identification if it’s wrong.) The one above was blooming in early June; the one below in late May. The similar Viburnum recognitum, which may also grow in our area, is sometimes classified as a variety of Viburnum dentatum.
Gray describes the genus and the species, which he places in the Euviburnum or Viburnum-proper section of the genus:
VIBÚRNUM [Tourn.] L. ARROW-WOOD, LAURESTINUS. Calyx 5-toothed. Corolla spreading, deeply 5-lobed. Stamens 5. Stigmas 1-3. Fruit a 1-celled 1-seeded drupe, with soft pulp and a thin-crustaceous (flattened or tumid) stone. —Shrubs, with simple leaves, and white (rarely pink) flowers in flat compound cymes. Petioles sometimes bearing little appendages which are evidently stipules. Leaf-buds naked, or with a pair of scales. (The classical Latin name, of unknown meaning.)
§ 3. EUVIBÚRNUM Koehne (restricted). Winter-buds scaly; leaves pinnately veined (except in V. acerifolium), the veins straightish and terminating in coarse teeth; cymes never radiant, peduncled; drupes blue to black; stone usually grooved.
Leaves cordate or subcordate at base, coarsely toothed, prominently pinnate-veined.
Stone very deeply sulcate ventrally; leaves rather slender-petioled.
V. dentàtum L. (ARROW-WOOD.) Smooth, 1-4.5 m. high, with ash-colored bark; leaves broadly ovate, glabrous, or with hairy tufts in the axils beneath, very numerously sharp-toothed and strongly veined, 5-8 cm. long; fruit globose-ovoid, 6 mm. long; cross-section of stone between kidney- and horseshoe-shaped. — Wet places, N. B. to n. Ga., w. to w. N. Y. and s. Ont. June, July.