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IDENTIFICATION OF CHESTNUT (CASTANEA) |
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IDENTIFICATION OF
CHESTNUT (CASTANEA) SPECIES GENERAL KEY 1a.
Leaves smooth between the veins on both sides (even when young), lacking
hairs or stalked glands (sometimes glands are present but lack stalks; the
veins are sometimes hairy in young leaves) . . . . go to 2 1b.
Leaves (especially sun leaves) densely hairy below when young (at least in
patches) or at least minutely stalked-glandular below or some combination of
glands and hairs . . . . go to 4 2a. Leaf teeth represented by bristles;
nut one in a bur. Rare tall tree species of Central and 2b. Leaf teeth broad and curving
triangular though commonly ending in a bristle; nut two or more in a bur.
Common. . . . . go to 3 3a.
With one distinct long trunk; leaves often thin and dull on top, usually long (5–10 inches), lance-shaped and narrowing to a fine
point (but shade leaves are commonly rather short and broad), broadly vee-shaped at base, mid-vein often with long appressed
hairs; branchlets lacking hairs, brown late in season; nuts small, about
one-half inch in width; spines thin, easily bent with finger . . . . American
Chestnut (C. dentata) 3b.
Trunks often more than one, branching near ground; leaves often firm and
glossy on top, usually short (3–7 inches but occasionally very long) and
ovate to elliptical, generally rounded at base, midvein
often with spreading hairs; branchlets occasionally with long, coarse hairs,
gray-green late in season; nuts usually up to 1 inch in width; spines
thicker, stiff . . . . Chinese
Chestnut or Chinese-American hybrid 4a. Trees . . . . go to 5 4b. Shrubs, occasionally becoming small
trees . . . . go to 7 5a.
Young leaves densely hairy below but without stalked-glandular hairs (except often glandular on midvein),
hairs each branching from the base; nuts 2–3 in a bur, wider than long . . .
. Chinese Chestnut (C. mollissima)
see also video1 5b.
Young leaves with both hairs and stalked glands below, the stalked glands
brownish, spherical or flattened . . . . go to 6 6a. Leaves 5–8 inches long, broadest below
the middle, variously shallowly or deeply toothed, glands mostly occurring
near midvein and side veins; smallest branches
brown, thick, with very short, weak, simple hairs . . . . European
Chestnut (C. sativa) 6b. Leaves 3–6 inches long, broadest in
the middle or above the middle, weakly toothed, the teeth often only
bristles, glands many, all over the lower surface of the leaf; smallest
branches reddish brown, thin, more strongly hairy at least when young . . . .
Japanese
Chestnut (C. crenata) 7a.
Young leaves not hairy but with glands below; nuts usually three in a bur.
Asian . . . . Seguin Chestnut (C. seguinii) 7b.
Young leaves densely hairy below (at least when young), not glandular except
on midvein or veins; nuts one in a bur . . . . go to 8 8a. Mature bur densely spiny, bur
appearing velvety. Southeastern mountains. (A form named Chinknut (C. ×neglecta)
with less hairy, thin leaves is apparently a hybrid with C. dentata.) . . . . Allegany Chinkapin
(C. pumila) 8b. Mature bur with more distant spines
and appearing rough. Uncommon, southeastern . . . . Trailing Chinkapin (C. alnifolium) For more
identification information, see also the Web site of Paul Sisco: ______________________________________________________________ QUICK KEY TO COMMON CHESTNUTS 1a.
Leaf stalks long, to 1¼ inches long or more . . . . European
Chestnut 1b.
Leaf stalks short, seldom more than 1 inch, usually much shorter, 1/4 to 1/2
inches long. . . . go to 2 2a. Leaves long and narrow, gradually
narrowing at the base, smooth on the underside when young excepting long
hairs on the veins . . . . American
Chestnut [movie] 2b. Leaves broad and elliptical, abruptly
narrowing at the base, densely hairy on the underside when young . . . . go to 3 3a.
Leaf teeth triangular . . . . Chinese
Chestnut 3b.
Leaf teeth merely stiff hairs on the margins . . . . Japanese
Chestnut ANOTHER VERSION: SECOND KEY TO COMMON CHESTNUTS 1a. Leaf stalks long, to 1¼ inches
long or more . . . . European
Chestnut 1b. Leaf stalks short, seldom more than
1 inch, usually 1/4 to 1/2 inch long . . . go to 2 2a. Leaf teeth weakly developed,
mostly just stiff hairs on the leaf margins . . . . Japanese
Chestnut 2b. Leaf teeth triangular . . . go
to 3 3a. Leaves broad and elliptical,
abruptly narrowing at the base, densely hairy on the underside when young;
spines of burr thicker, stiff and resisting bending with finger. . . . Chinese
Chestnut 3b. Leaves long and narrow,
gradually narrowing at the base, smooth on the underside when young excepting
long hairs on the veins; spines of burr thinner, easily bent with finger . .
. . American
Chestnut [movie] _________________________________________________________________ NOTES ON THE ABOVE KEYS These keys are modified
and expanded from Arthur H. Graves' "Keys to Chestnut Species,"
40th Annual Report of the National Nut Growers Association, 95–107, 1950.
Hairs that are characteristic of certain chestnut species are deciduous and
may completely disappear (except for some hairs on the ribs) from the
underside of a leaf as the leaf matures. To determine hairiness, in summer it
is important to examine small leaves from the extreme ends of branches; a
sample taken for identification should be a twig from the end of a branch,
with several attached leaves. Fold the leaf back to expose the underside as a
ridge and examine from the side with a hand-lens to see the hairs best. The
very smallest early spring leaves of American chestnut, however, are felted
underneath with simple hairs and may be densely glandular. Also, hybrids
between the various Chestnut species are very difficult to identify.
Hairiness of leaves is a genetically dominant character and hairs that branch
at the base should be present on the young leaves of Chinese-American
hybrids. Hairs are absent, however, on leaves of some trees resulting from
crosses between the two hybrids (whenever a plant has double genes for the
recessive hairless trait). A good rule of thumb is to assume you have a
hybrid unless you have good reason to believe otherwise, such as having all
characters agree exactly with the key. MORE NOTES ON
CHESTNUTS, THEIR HYBRIDS, American Chestnut
leaves are dull (matte), light green, thin and limp (unless they are sun
leaves), their burs have fine hair-like spines, and the nuts are small,
usually with a clear "sunburst" on the scar; while Chinese and
European Chestnut leaves are dark glossy green on top (compare upper and
lower surfaces by folding the leaf over), more leathery and stiff (even in
the shade), and have burs with thick, stiff spines and larger nuts, these
usually lacking the vascular bundle "sunburst". Sometimes on the
underside of pure American Chestnut leaves a few simple hairs may be found on
the midrib or a few glands between the veins. American-European hybrids often
have simple hairs on the ventral (top) side of the leaf midvein.
A common European-Japanese hybrid has long leafstalks and spiny leaf teeth. According to K.C. Nixon's Castanea
treatment in Flora of North America, European Chestnut differs from the
American by star-forming hairs on the underside of its leaves, which have
long leaf-stalk (to 1¼ inches or more), while Chinese Chestnut has twigs with
spreading hairs and lacks the glands found on the underside of the leaves of
both American and European. Some horticultural
hybrids are the Blaringhem Chestnut (mollissima × sativa), Burbank Chestnut (mollissima × pumila), Couderc Chestnut (crenata
× sativa), Endicott Chestnut (crenata
× dentata), Vanfleet
Chestnut (crenata × pumila),
Morris Chestnut (alnifolia × mollissima), and Pulchella
Chestnut (pumila × sativa). There are
also many horticultural clones, including American Chestnuts with fairly
large nuts. The "chestnut oaks" have leaves much like those of the
chestnut tree, but have blunt leaf teeth that end in a thick, short, blunt
point, while those of genuine chestnuts are narrow and sharp, and often
ending in a bristle. The leaf-stalks of chestnut oaks are usually considerably
longer than those of true chestnuts. If still unsure, check branches and
ground for acorns. The Horsechestnut,
a common street tree, differs from true chestnuts in having five or more
leaflets on each leafstalk. Beech leaves have hairy margins, which are not
infolded. American Chestnut is
more cold-hardy than Chinese or European, and collections from northern areas
or high elevations (such as the in The Allegheny Chinkapin is a small tree or shrub of dry woods, COMPARISON OF AMERICAN
AND CHINESE CHESTNUT TRAITS AMERICAN CHESTNUT LEAVES: Leaves
flexible; lanceolate; teeth large, sharp; both sun and shade leaves lacking
hairs between the veins. STIPULES: narrow;
0.1-0.2 cm (about 1/32" to 3/32") wide at base; falling off early. TWIGS: red-brown to
brownish green; smooth; lenticels (pores) small, 0.1 mm (very tiny, like
powder). BUDS: red-brown to
yellow-brown; sharp, width only half that of length; angled outward from
stem. NUTS: far ends pointed;
hairs on 1/3 to 2/3 of length; sunburst present. BURS: spines mostly 0.5
mm (about 1/64") in diameter and 2-3 cm (about 3/4" to 1 1/4")
in length. CHINESE CHESTNUT LEAVES: shiny;
leathery; ovate; teeth relatively small; leaf base often rounded; sun leaves
hairy below between veins. STIPULES: triangular;
0.5-1.0 (about 1/4" to 3/4") cm wide at base; persistent on twig. TWIGS: tan or very
green; hairy; lenticels (pores) large, 0.5 mm (about 1/64"). BUDS: tan to dull
brown; rounded, nearly as wide as long; angled towards stem tip. NUTS: far ends rounded;
hairs only near end; sunburst usually absent. BURS: spines mostly 1 mm
(about 1/32") in diameter and 1-2 cm (1/3" to 3/4") in length.
See also (click) Movie on American
Chestnut and
THE
AMERICAN CHESTNUT FOUNDATION The American Chestnut
Foundation New York State Chapter is a not-for-profit organization dedicated
to re-establishing the American Chestnut in our forests. The American
Chestnut was largely destroyed by a blight in the 1930's, and is much missed
because of its imposing size, sweet nuts, and straight trunks that made
excellent, rot-resistant lumber. Various programs, including plant breeding
for blight-resistance, are supported. Members of the Chapter meet once a year
to exchange information, stories about chestnuts, listen to talks, and
distribute nuts from living trees for people to plant (this maintains the
biological diversity needed for the hoped-for future stands of
blight-resistant American chestnuts). The public is invited to join. Inquiries
about membership can be directed to: Herbert F. Darling And check out the
American Chestnut Foundation's web site, www.ACF.org . More resources art at: |
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