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36 i d e n t i f y i n g i o wa’s t r e e s Key to Oaks (Quercus) 1. Largest veins extending beyond tips of lobes or teeth (or beyond apex of leaf if it is neither toothed nor lobed), forming short bristles (red oaks): 2 1. Lobes or teeth not bristle-tipped (white oaks): 8 2. Leaves unlobed or shallowly 3-lobed: 3 2. Leaves 5- to 9-lobed: 4 3. Leaves elliptic or oblong, not lobed: shingle oak, Q. imbricaria 3. Leaves obovate, shallowly 3-lobed on upper half: blackjack oak, Q. marilandica 4. Length of leaf lobes less than, equal to, or slightly greater than the width of the central, undivided portion of the blade: red oak, Q. rubra 4. Length of largest leaf lobes 2 to 6 times greater than the width of the central, undivided portion of the blade: 5 5. Fully grown buds 1/4 to 1/2 inch long, densely covered with brown hairs; scales around rim of acorncup loosely attached, forming fringe: black oak, Q. velutina 5. Fully grown buds 1/16 to 1/4 inch long, either glabrous or only partially hairy; scales of acorn-cup all tightly attached: 6 8. Flowers and fruits in racemes on leafy shoots (twigs) of current growing season; leaves frequently with orange hairs along lower portion of midvein beneath; tall tree with scaly bark: black cherry, P. serotina 8. Flowers and fruits in small, umbellike clusters on twigs of previous growing season; leaves lacking orange hairs beneath; small tree: pin cherry, P. pensylvanica 9. Leaves lanceolate to oblong, at least twice as long as wide: 10 9. Leave oval to elliptic, less than twice as long as wide: 11 10. Fruits fuzzy: peach, P. persica 10. Fruits smooth: goose plum, P. hortulana 11. Leaf teeth sharp-pointed (fig. 27a): 12 11. Leaf teeth blunt or rounded (fig. 27b): Canada plum, P. nigra 12. Flower stalks glabrous; thicket forming shrub or small tree, common throughout state: American plum, P. americana 12. Flower stalks hairy; tree with single stem, uncommon: big-tree plum, P. mexicana s u m m e r k e y s t o i o wa’s t r e e s 37 9. Leaf blades 2 1/2 to 5 inches long with 2 small, earlike projections at base; acorns with stalks longer than leaf petioles; cultivated tree: English oak, Q. robur 9. Leaf blades 5 to 9 inches long without earlike projections at base; acorns not stalked or with stalks shorter than leaf petioles; native tree: white oak, Q. alba 10. Leaves toothed or shallowly lobed (i.e., spaces between lobes or teeth extending less than half the distance between margin and midvein): 11 10. Leaves deeply lobed (i.e., at least some of the spaces between lobes extending more than half the distance between margin and midvein): 13 11. Petioles 1/8 to 3/8 inch long; small, shrubby tree bearing acorns when only a few feet tall: dwarf oak, Q. prinoides 11. Petioles 1/2 to 1 1/2 inches long; a tree: 12 12. Each half of leaf with 8 to 13 often sharp-pointed teeth; acorns unstalked or with very short stalks; tree native in dry upland woods, rarely cultivated: chinkapin oak, Q. muhlenbergii 12. Each half of leaf with 4 to 6 blunt teeth or lobes; acorns with stalks 1 to 4 inches long; tree native in moist, low-lying woods, frequently cultivated: swamp white oak, Q. bicolor 6. Acorn hemisphere-shaped, 3/8 to 1/2 inch long, with a saucer-shaped cup covering only the base of the nut; tree cultivated throughout state but native only in southeastern corner, usually in low-lying woods near streams: pin oak, Q. palustris 6. Acorn longer than wide, 1/2 to 1 inch long, with a bowl-shaped or cone-shaped cup covering about 1/2 of the nut; native or cultivated: Two very similar trees will key out here, variously regarded as different species or varieties of a single species. Both are quite variable and their characteristics overlap. Typical individuals can be identified as follows: 7. Nut egg-shaped with concentric grooves around the apex; cup bowl-shaped; tree cultivated in Iowa but not native: scarlet oak, Q. coccinea 7. Nut elongated, often with dark vertical stripes but lacking concentric grooves around the apex; cup cone-shaped; native tree, occasionally cultivated: Hill’s oak or northern pin oak, Q...

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