CAPRIFOLIACEAE: Honeysuckle family

KEY TO VIBURNUM SPECIES

1. Leaf blade palmately veined and palmately lobed, rarely some unlobed .......... 2

2. Petiole lacking large glands ............................... V. acerifolium

2. Petiole with 1-6 large glands on upper portion near blade .................. 3

3. Upperside of fresh petioles with a rounded depression ca 1.1-1.7 mm across, glands 0.4-1 mm across ..................... V. opulus var americanum

3. Upperside of fresh petioles with a V-groove ca 0.5-0.9 mm across, glands 1-2.7 mm across ............................ V. opulus

1. Leaf blade pinnately veined, not lobed (sometimes a few leaves lobed in V. molle ) .................................................... 4

4. Leaf blade with 1-3 prominent teeth per cm at mid-edges .................... 5

5. Largest blade nearly sessile to petiole averaging to 13 mm .............. 6

6. Bark of older twigs flaking mildly; petiole averaging under 10 mm ................................... V. rafinesquianum

6. Bark of older twigs tight; petiole averaging over 10 mm ...................................................... V. bracteatum

5. Largest blade with petiole averaging over 13 mm ......................... 7

7. Most leaf blades with (18)20-30 pairs of teeth, base cordate, lowest (2)3 pairs of lateral veins arising near petiole; stipules 1.1-3.2 X ca 0.3 mm .................................................... V. molle

7. Most leaf blades with less than 20 pairs of teeth, base narrowed to subcordate, lowest (2)3 pairs of lateral veins not all arising near petiole; stipules absent or rarely a few ............... V. dentatum

4. Leaf blade entire or nearly so OR with 5 or more teeth per cm at mid-edges ............................... 8

8. Twigs covered with a dense crust of hairs, character of hairs obscured, epidermis not evident ........................ V. rhytidophyllum

8. Twigs glabrous to densely hairy but epidermis and character of hairs clearly evident .................................. V. obovatum