I know it s an oak, but which one is it?

To: Stockton Natural World Explorers From: jc Re: A Brief Guide to Stockton s Oaks Date: October 22, 2014 I know it s an oak, but which one is it? Our campus hosts at least ten species of oaks, including two or three that are a challenge to find (and three or four that are hard to miss.) If you can find each of them in one semester, you have proven yourself a knowledgeable explorer of Stockton s forest. The pages that follow are intended to help you with that challenge they are a condensed and somewhat revised version of the more general guide available in A Beginner s Key to Stockton s Tall Woody Plants. First, some general tips: 1. Oaks can be difficult to identify. Several species are close look-alikes; leaf shapes are often variable (even on a single tree); and the possibility of hybrid oaks (with parents from two different species) adds complexities. 2. Fall is by far the best time to learn them. The leaves are fully developed and often show color differences that make identification easier. Acorns are ripe in fall and can provide more clues, although.. 3. Acorns are a sufficient but not necessary characteristic of oaks. If you see a tree or shrub with acorns, you know it s an oak, but you will often come upon oaks with no acorns in sight. All species show wide variations in their acorn production from year to year from few or none in some years to tens of thousands in mast years. 4. Once you know you are looking at an oak, study the leaf margins to sort the tree to its sub-group. The red oaks have bristles on their tips; the white oaks do not. Go next to the end buds. The buds

on red oaks tend to be larger and/or more pointed than those on the white oaks (which are generally smaller and often rounded). The most serious botanists rely more on end buds (and acorns when available) to identify oak species than they do the leaves which can fool even veteran botanists. 5. Of our ten campus species, six are members of the red oak group (with leaf bristles and larger and/or more pointed end buds) and four are members of the white oak group (no bristles, smaller/more rounded end buds). 6. Each group includes one shrub. The red oak shrub is Quercus ilicifolia, scrub oak (very common on campus). The white oak shrub is Quercus prinoides, dwarf chestnut oak (one of the two or three most challenging oaks to find on Stockton property). 7. A sense of the ten species relative abundances on campus helps you know which to expect most often. In order of abundance the red oaks are -- Two very common species: Quercus ilicifolia (scrub oak) Q. coccinea (scarlet oak) Two less common species: Q. velutina (black oak) Q. falcata (southern red oak) And two species you must look long and hard to find: Q. phellos (willow oak) Q. marilandica (blackjack oak) Note: this guide ignores a seventh member of the red oak group, Q. palustris (pin oak). That species seems to exist on campus only where it was planted near the buildings decades ago and apparently fewer than half a dozen individual trees now survive. (The species is not native to the NJPB.) Among the white oaks in order of abundance, we have One extremely common species: Q. alba (white oak) Two less common species: Q. stellata (post oak) Q. prinus (chestnut oak, a.k.a. Q. montana) And one hard-to-find, small shrub: Q. prinoides (dwarf chestnut oak) 2

Two Red Oak Oddities: Q. ilicifolia and Q. phellos These two species have bristles on their tips like all red oaks, but are otherwise unusual members of the group. The first is a shrub; the second has no lobes on its leaves and can t stand fire. Quercus ilicifolia (scrub oak) is a shrub, generally showing multiple trunks, though it sometimes grows nearly to tree height. Its abundance on campus is at least partially due to its resistance to fire. Habitat[s]: Dry uplands throughout southern NJ; very common in the NJPB and on-campus, one of our most numerous woody plants (and often misidentified as one of the other oaks). Autumn clues: only tall shrub with bristled lvs; leaf shape variable but textbook lf has three prominent lobes at tip like a trident; lf undersides pubescent (fuzzy). Look-alikes: Easily mistaken for other red oaks especially Q. marilandica, which has thicker leaves with more yellow below. To contrast other Quercus, look for trident textbook lvs on ilicifolia and note the growth pattern; its closest look-alikes are all trees. If you can find Quercus phellos (willow oak) on campus, you have proven yourself a sharp-eyed observer. Its scattered presence on here seems evidence that Coastal Strip soils overlay NJPB soils in some areas. Habitat[s]: Martine, a southern tree reaching the northernmost part of its range in central NJ.found in the hardwood swamps of the Coastal Plain, but not [in NJPB because] extremely fireintolerant. Autumn clues: willow-like, lanceolate lf with single bristle at tip; acorns (when present) small w/shallow cups. Look-alikes: None. No other SJ tree features the odd combination of unlobed, lanceolate leaf with a single bristle at the tip. 3

The Red Oaks Two Closest Look-Alikes: These two species -- probably the two woody plants most difficult to distinguish on campus -- demonstrate why botany can be a life-long challenge! And don t be deceived by these two drawings; they are not always so different. Quercus coccinea (scarlet oak) above and its near twin to the right. Leaf-shape differences are more obvious in these drawings than in many real-world examples. Habitat[s]: Common in dry uplands of campus and elsewhere in SJ and NJPB Autumn clues: lvs usu show deep sinuses with narrow mid-rib; acorns oft show rings around tips; fall lvs become scarlet (October). W. Cook: The sinuses are c- shaped, which helps you remember coccinea. Fuzzy white top half of end buds. Look-alikes: Separate from Q. falcata and Q. marilandica by lobing patterns; separate from Q. ilicifolia (shrub) by growth pattern. The very similar Q. velutina has lvs usu slightly shallower sinuses; twig end buds larger, 4-angled and covered with w/many grayish hairs, not silver-white tips. Quercus velutina, (black oak). Subtle differences in the end buds and in the acorns are generally the most reliable keys not leaf shape. Habitat[s]: Same as Q. coccinea common in uplands of SJ and NJPB Autumn clues: lvs very variable in size and shape, oft close to Q. coccinea, but mid-rib of lvs usu wider; end buds large, 4-angled, and wooly gray; no rings around acorn tips; by Oct fall lvs oft more orange than red. Look-alikes: The four-sided, very large end buds (w/o silver tips) on velutina may be most reliable clue to distinguish it from coccinea.. To separate from other Quercus, see Q. coccinea Lookalike clues. 4

Two Red Oaks With Most Variable Leaves* * maybe since all oaks show variable leaves, it s a tough call. Quercus falcata (southern red oak) Habitat[s]: Uplands of SJ mostly south of Mullica River; on campus less common than two species above. Autumn clues: central lobe oft usu extends well beyond other lobes like a red-neck giving you the finger. End buds pointed, red-fuzzy, variable in size, generally smaller than other red oaks. Look-alikes: Lf shape varies vary, but no other oak shows such a long middle finger on so many lvs; falcata = sickle-shaped. Quercus marilandica (blackjack oak) Habitat[s]: Dry, most-fire-prone uplands of the NJPB; a dominant species in Pygmy Plains, but only a handful on campus a challenge for alert, campus explorers Autumn clues: thick, tough lvs variably shaped; many (not all) show spatulate-lobing; dark green above and almost golden below. Look-alikes: See Q. ilicifolia, a shrub (and sometimes hybrid partner), w/slightly thinner lvs not so golden below, many lvs (not all) more lobing, not as many spatulate lvs as Q. marilandica. 5

The White Oaks Two Closest Look-Alikes: Quercus alba (white oak) Habitat[s]: Common in uplands of campus and elsewhere in SJ and NJPB and occ in lowlands as well. Probably the second-most common tree on campus (after Pinus rigida). Autumn clues: lobes numerous (5+) and lvs most variable of the unbristled ( white ) oaks; bark usu gray or white and oft flakey; acorns (if present) oft oblong shape, ~1 inch long. Look-alikes: Q. stellata usu shows fewer lobes usu wider, especially cross lobe. Q. prinus has much smaller, more regular, crenate (almost tooth-like) lobing. Quercus stellata (post oak) Habitat[s]: Fairly common on campus and NJPB, especially in the driest, most fire-prone areas. Seems better adapted to fire than other white oaks. Autumn clues: Wide central lobe of most lvs distinctive -- like a cross-post; lvs oft fuzzy/hairy below; bark ridged, not flakey; acorns (if present) ~egg-shaped Look-alikes: Q. alba lvs usu more lobing, narrower mid-rib, and more deeply cut sinuses, undersides not fuzzy; also subtly different bark. 6

Two White Oaks with Wavy-Margined (= Crenate) Leaves Quercus prinus (chestnut oak) Habitat[s]: Fairly common to common in sandy uplands of SJ and NJPB; common on campus in a few such areas, but generally less numerous than Q. falcata and much less numerous than Q. alba. Autumn clues: many small lobes = crenate pattern; acorns (if present) distinctly large, oft 1.5 in; bark often shows long ridged grooves running lengthwise down the trunk. Look-alikes: Q. prinoides is a small shrub with similar lvs but sharper (slightly more pointed) crenate lobes; that species also much less frequent on campus than Q. prinus. Quercus prinoides (dwarf chestnut oak) Habitat[s]: Dry uplands, especially in the NJPB. A challenge to find on campus, although a few occur in the woods not far from Lake Fred and a number of individuals occur on Delaware Avenue. Autumn clues: A shrub usually <4 ft. Lf lobes are small and fairly sharp crenate. Acorns are smaller than marbles <1. Leaf tips have little nipple-like extensions you can see with a magnifying glass. Look-alikes: Q. prinus has similar but much larger leaves and. when fully grown, is 20x taller and has much larger acorns. Q. prinus also lacks the tiny nipple tips on the leaves just visible on prinoides. 7