Magnolia acuminata
Magnolia
cucumber-tree
magnolia
dark gray, furrowed.
and foliar buds silvery-pubescent.
blade broadly ovate-elliptic, oblong to oblong-obovate, rarely somewhat rotund, (5-)10-25(-40) × 4-15(-26) cm, base cuneate to truncate or broadly rounded, often somewhat oblique, apex acuminate;
surfaces abaxially pale green to whitish, pilose to nearly glabrous, adaxially green, glabrous or rarely scattered pilose.
blade: base deeply cordate or auriculate or cuneate to abruptly narrowed or rounded, margins entire, apex obtuse or acute to acuminate;
surfaces abaxially chalky white or green to glaucous, pubescent or glabrous.
slightly aromatic, 6-9 cm across; spathaceous bracts 2, abaxially silky-pubescent;
tepals erect, strongly glaucous to greenish or sometimes yellow to orange-yellow, outermost tepals reflexed, much shorter, green;
stamens (50-)60-122(-139), 5-13 mm;
filaments white;
pistils (35-)40-45(-60).
protogynous, appearing with or before leaves;
tepals 9-15, petaloid, usually spreading, creamy white, rarely greenish, yellow, or orange-yellow, outermost tepals sepaloid, sometimes strongly reflexed, greenish;
stamens on elongate torus, early deciduous;
filaments white or purple, very short;
anthers introrse or latrorse.
heart-shaped, somewhat flattened to somewhat globose, 9-10 mm, smooth, aril reddish orange.
with red, pink, or orange oily aril, extruded from follicles and suspended by funiculi.
homogeneous.
homogeneous or diaphragmed.
oblong-cylindric, often asymmetric, 2-7 × 0.8-2.7 cm;
follicles short-beaked, glabrous.
persistent, coalescent, forming conelike aggregate, abaxially dehiscent.
=19.
=76.
Magnolia acuminata
Magnolia
The vernacular name, cucumber-tree, alludes to the resemblance of the follicetum to the young fruit of cucumber. It is the only magnolia species in the flora that occurs naturally in Canada.
Studies of Magnolia acuminata have failed to reconcile the nature of variation in this widespread species. In an attempt to settle differences in variation patterns, J.W. Hardin (1954) recognized four infraspecific taxa in M. acuminata. Later (1972, 1989) Hardin abandoned his earlier views for a more conservative stance, stating that variation in M. acuminata lacked any consistent pattern or geographic correlation. This is the view taken here–no infraspecific taxa are accepted for M. acuminata at this time. Its flowers are normally greenish and glaucous or sometimes yellow to orange-yellow, less showy than those of other magnolias in the flora. In southern areas, trees with yellow to orange-yellow flowers (originally described by Michaux as M. cordata) occur in North Carolina, Georgia, Alabama, and perhaps elsewhere, together with trees that bear normal greenish flowers. Both filiform and flagelliform trichomes occur on the leaves; cylindric trichomes also occur.
Magnolia acuminata is of value to horticulturists because no other species of the genus has yellow tepals. Magnolia acuminata contains major quantities of xanthophyll lutein-5,6-epoxide and, in smaller amounts, acarotene-5,6-epoxide. Although this carotenoid occurs randomly throughout populations of M. acuminata, often it is masked by chlorophyll and not visibly expressed. Sometimes the carotenoid pigment shows through, as in the hybrid M. acuminata × M. denudata 'Elizabeth'. In that cross the M. acuminata parent tree was a nondescript plant with greenish flowers; yet out of this hybrid came 'Elizabeth', a stunning plant with light canary yellow flowers, a result completely unexpected. A thorough field study of M. acuminata is clearly warranted, and further investigation of the carotenoid flower pigments is needed to clarify the taxonomy of this widespread tree.
The largest known tree of Magnolia acuminata, 29.6m in height with a trunk diameter of 1.26m, is recorded from a specimen cultivated in Waukon, Iowa (American Forestry Association 1994).
The Cherokee and Iroquois tribes used Magnolia acuminata, largely the bark, as an analgesic, antidiarrheal, gastrointestinal aid, anthelmintic, toothache remedy, and for various other uses (D.E. Moerman 1986).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species ca. 120 (8 in the flora).
All species of Magnolia in the flora are cultivated. Many of the Asiatic taxa are also grown in the flora area. Numerous hybrids and cultivars from those taxa have been introduced to horticulture.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaf blade deeply cordate to auriculate at base. | → 2 |
1. Leaf blade cuneate to abruptly narrowed or rounded at base. | → 5 |
2. Leaf blade abaxially chalky white, sometimes pale green to glaucous, pubescent; foliar buds, twigs, and follicles pubescent. | → 3 |
2. Leaf blade abaxially green or glaucous, glabrous; foliar buds, twigs, and follicles glabrous. | → 4 |
3. Trees to 32m; flowers solitary; follicetums globose-ovoid, 5–8 × 5–7cm; leaf blade 50–110cm; stamens (300–)350–580; pistils 50–80. | M. macrophylla |
3. Trees to 12m; flowers solitary or often paired; follicetums cylindric to nearly ovoid, 2.5–6.5 × 1.5–4cm; leaf blade 17–56cm; stamens 170–350; pistils 20–50. | M. ashei |
4. Leaf blade rhombic-obovate to obovate-spatulate or oblanceolate, usually more than 25cm, gradually tapered from broadest part to base; stamens 100–200, 8–14mm; follicetums 5.5–10 × 2.5–5cm. | M. fraseri |
4. Leaf blade predominantly pandurate to broadly rhombic-spatulate, usually less than 25cm, abruptly tapered from broadest part to base; stamens 83–137(–150), 4.5–8(–10.5)mm; follicetums 4–6 × 2.5–3.5cm. | M. pyramidata |
5. Leaf blade abaxially chalky white to glaucous, glabrous or silky-pubescent, somewhat leathery. | M. virginiana |
5. Leaf blade abaxially green to red-brown, glabrous, felted, or pilose, thin- to thick-leathery or not leathery. | → 6 |
6. Trees evergreen; leaf blade thick-leathery, abaxially glabrous or red-brown felted, adaxially lustrous green; flowers 15–30(–45)cm across, strongly lemony fragrant. | M. grandiflora |
6. Trees deciduous; leaf blade thin, not leathery, abaxially pale green to whitish, glabrous or pilose, adaxially green; flowers 5.5–11cm across, malodorous or aromatic. | → 7 |
7. Leaves usually in terminal whorl-like clusters; leaf blade cuneate to long-tapered at base; flowers malodorous, 5.5–11cm across; tepals creamy white, 8–12cm, spreading, outermost tepals reflexed, greenish; follicetums 6–10 × 2–3.5cm; follicles long-beaked. | M. tripetala |
7. Leaves not in whorl-like clusters; leaf blade cuneate to truncate or rounded, slightly oblique at base; flowers aromatic, 6–9cm across; tepals greenish, glaucous, occasionally yellow to orange-yellow, usually less than 8cm, erect, outermost tepals reflexed, greenish; follicetums 2–7 × 0.8–2.7cm; follicles short-beaked. | M. acuminata |
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