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Juglans microcarpa

(Little Walnut)

Overview

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Interesting Facts

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Common Names

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Click on the language to view common names.

Common Names in English:

Little Walnut, River Walnut, Texas Walnut

Common Names in French:

Namboca, Nogal, Nogalito

Common Names in German:

Felsen-Walnuß

Common Names in Spanish:

Namboca, Nogal, Nogalito

Common Names in unspecified:

Little Walnut

Description

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Family Juglandaceae

Trees or rarely shrubs , deciduous, semievergreen, or evergreen , monoecious or rarely dioecious; bark tight (or exfoliating) . Branchlets with solid or chambered pith . Terminal buds subglobose or ovoid to oblong , naked or with scales . Stipules absent. Leaves alternate (or opposite), odd- or even-pinnate, sometimes trifoliolate , rarely simple ; leaflets with glandular , peltate scales, often resinous and aromatic , particularly conspicuous abaxially on young leaves and twigs , margin serrate or rarely entire. Inflorescences pendulous or sometimes erect , lateral or terminal, on reduced shoots arising on branchlets of previous year (old growth) or on current year’s growth (new growth), of several types: androgynous panicle with male, lateral spikes and female, central spike; androgynous panicle with male, mainly lateral spikes and female, central spike male at apex; cluster of male spikes and solitary female spike; or solitary male and female spikes. Flowers unisexual , anemophilous , rarely entomophilous. Male flowers subtended by an entire or 3-lobed bract; bracteoles 2 or absent; sepals 0-4, adnate to receptacle when present; stamens 3-40(-100), inserted on receptacle; filaments short to nearly absent, free or united at base ; anthers glabrous or pubescent , 2-loculed, dehiscing longitudinally. Female flowers with an entire or 3-lobed bracts; bracteoles 2 or 3 (or absent) ; sepals 0-4, adnate to ovary, free at apex; gynoecium of 2 carpels united into an inferior ovary , 1-loculed, but at base 2-4(-8) -loculed; style 1, short or elongate , rarely absent; stigmas 2, carinal or commissural , sometimes 4-lobed, plumose or fleshy ; ovule 1, orthotropous . Fruiting spike elongate, and pendulous or short and erect, rarely conelike. Fruit a drupelike nut, 2-4(-8) -chambered at base, with a dehiscent or indehiscent husk , or a 2- or 3-winged or disc-winged nutlet . Seed solitary, without endosperm. Cotyledons 4-lobed, much contorted. Germination hypogeal or epigeal. 2n = (28), 32, (64) .

Nine genera and 60 or more species: mostly in temperate and subtropical regions of the N hemisphere; seven genera (one endemic) and 20 species (seven endemic, one introduced ) in China.[1]

Genus Juglans

Shrubs or trees , 3-50 m. Bark light to dark gray or gray-brown, smooth or split into ridges or plates . Twigs purplish brown, terete , stout, sparsely to densely covered with glands and capitate-glandular hairs , sometimes also with scales or fasciculate hairs, early in season with multiradiate hairs; leaf scars triangular or 3-lobed, large; pith chambered . Bud scales valvate , densely hirsute . Leaves usually odd-, sometimes even-pinnate; petiole and rachis with indument as twigs. Leaflets 5-25, sessile or subsessile , often aromatic , uniform in size or median leaflets largest, (2.5-) 4.3-15(-17.5) × 0.8-6.5 cm; surfaces usually with nonglandular hairs (simple and/or fasciculate), glandular hairs, sessile glands, and/or scales, sometimes glabrous . Staminate catkins solitary from 2d-year twigs, sessile; stamens 7-50 per flower, glabrous or pilose . Pistillate flowers solitary or in terminal racemes . Fruits nuts enclosed in husks , not compressed ; husks thick, indehiscent; nuts tan, neither compressed nor angled , grooved , ridged , rugulose , or smooth; shells thick. Seeds sweet. x = 16.

Species 21: North America, Mexico, West Indies, Central America, South America, Eurasia .

Juglans is a very important source of edible nuts, dyes, and wood for cabinet work, furniture, and construction. Juglans regia Linnaeus, the walnut of commerce, is widely cultivated in California; it is easily distinguished from native species by its leaves with 5-11 broad, entire leaflets and nuts with thin rugulose shells, not grooved or ridged. Because of its sensitivity to native pathogens , J. regia is usually grown as stem-grafts on roots of native or hybrid walnuts (see discussion under J. hindsii). Occasional seedlings of J. regia have been reported from the vicinity of cultivated plants , but these seldom, if ever, live to maturity.

The growth form , bark, and fruit are important taxonomically in Juglans, but these usually are not available on herbarium specimens. As with many woody plants , the first one or two leaves of the season (i.e. , the lowermost leaves on the twig ) are sometimes atypical in structure, having broader, blunter leaflets. The fasciculate hairs on the veins normally have more rays than those on the blade . In addition to the types of hairs described below, small multiradiate hairs are found on the immature twigs, petioles, rachises, and midribs . They are usually gone when the leaf is fully expanded, but they may persist for a short time afterwards.[2]

Physical Description

Species Juglans microcarpa

Shrubs or small trees , to 10 m. Bark medium gray, split into ± rough ridges . Twigs with distal edge of leaf scar notched , glabrous or bordered by poorly defined velvety zone; pith light to dark brown. Terminal buds globose to short-ovoid, not flattened, 3-5 mm. Leaves 12-29 cm; petiole 1-3(-4) cm. Leaflets 17-25, lanceolate or narrowly lanceolate, weakly to strongly falcate , 5.2-6.3(-9.6) × 0.8-1.1(-2.2) cm, margins entire or toothed , apex long-acuminate; surfaces abaxially with capitate-glandular hairs (sometimes becoming sparse late in season except along veins), often scattered scales , axils of proximal veins usually, not always, with prominent tufts of fasciculate hairs, adaxially with capitate-glandular hairs (late in season hairs sometimes becoming sparse except along veins) ; terminal leaflet usually small. Staminate catkins 3-7 cm; stamens 20-25(-35) per flower; pollen sacs 0.8-1 mm. Fruits 1-3, globose, 1.4-2.3 cm, smooth , with capitate-glandular hairs; nuts globose to depressed-globose, 1.1-1.7 cm, grooved , surface between grooves smooth. [source]

Specimens of Juglans microcarpa with larger leaflets (parenthetical numbers above) may result from introgression with J. major. These have sometimes been treated as J. microcarpa var. stewartii (I. M. Johnston) W. E. Manning, but W. E. Manning (1978) reported this variety only from Mexico. Intermediates between J. microcarpa and J. nigra (q.v. ) are also known. [source]

Habit: Tree , Shrub

Flowers: Bloom Period: February, March, April, May, June. • Flower Color: chartreuse, pale green, yellow-green

Size/Age/Growth

Size: 15-20' tall.

Habitat

Along creeks and rivers ; 200-2000 m [3].

Typically found at an altitude of 0 to 2,228 meters (0 to 7,310 feet).[4]

Biology

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Reproduction

Duration: Perennial

Growth

Culture: Space 12-15' apart.

Soil: Minimum pH: 6.1 • Maximum pH: 7.5

Sunlight: Sun Exposure: Full Sun .

Moisture: Drought Tolerance: High

Temperature: Cold Hardiness: 6a, 6b, 7a, 7b, 8a, 8b. (map)

Taxonomy

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Synonyms

Juglans rupestris Engelmann Ex Torrey

Notes

Publishing author : Berland. Publication : Berland. & Chovell, Diario Viage Comision de Limites Mier y Teran 276 (1850)cf. I. M. Johnston in Journ. Arn. Arb. xxv. 436 (1944)

Name Status: Accepted Name .

Last scrutiny: 15-Mar-2000

Similar Species

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Members of the genus Juglans

ZipcodeZoo has pages for 82 species, subspecies, varieties, forms, and cultivars in this genus:

J. ailanthifolia (Japanese Walnut) · J. ailanthifolia var. cordiformis (Heartnut) · J. ailantifolia (Japanese Walnut) · J. australis (Nogal Criollo) · J. bixbyi (Bixby Walnut) · J. boliviana (Bolivian Walnut) · J. californica (Northern California Black Walnut) · J. californica S.Watson var. californica S.Watson (Southern California Black Walnut) · J. californica var. californica (California Walnut) · J. cinerea (Butternut) · J. cinerea 'Bountiful' (Butternut) · J. cinerea 'Loumis' (Butternut) · J. cordiformis 'Campbell Cw1' (Heartnut) · J. cordiformis 'Campbell Cw3' (Heartnut) · J. cordiformis 'Campbell Cww' (Heartnut) · J. cordiformis 'Frank' (Heartnut) · J. cordiformis 'Imshu' (Heartnut) · J. cordiformis 'Locket' (Heartnut) · J. cordiformis 'Marvel' (Heartnut) · J. cordiformis 'Mitchell Hybrid' (Heartnut) · J. cordiformis 'Rhodes' (Heartnut) · J. cordiformis 'Simcoe' (Heartnut) · J. cordiformis 'Stealth' (Heartnut) · J. cordiformis 'Wright' (Heartnut) · J. hindsii (Northern California Black Walnut) · J. illinoinensis (Pecan) · J. intermedia (Intermediate Walnut) · J. jamaicensis (Walnut) · J. major (Arizona Black Walnut) · J. mandshurica (Manchurian Walnut) · J. microcarpa (Little Walnut) · J. microcarpa var. microcarpa (Little Walnut) · J. microcarpa var. stewartii (Stewarts Little Walnut) · J. microcarpa var. stewartii (I.M.Johnst.) W.Manning (Stewart's Little Walnut) · J. microcarpa subsp. major (Little Walnut) · J. neotropica (Andean Walnut) · J. nigra (Black Walnut) · J. nigra 'Beineke 11' (Black Walnut 'beineke 11') · J. nigra 'Black Gem' (Black Walnut) · J. nigra 'Daniels' (Black Walnut) · J. nigra 'Emma Kay' (Black Walnut) · J. nigra 'Football 2' (Black Walnut) · J. nigra 'Krause' (Black Walnut) · J. nigra 'Kwik Krop' (Black Walnut) · J. nigra 'Laciniata' (Black Walnut) · J. nigra 'Lamb's Curly' (Black Walnut) · J. nigra 'Ridgeway' (Black Walnut) · J. nigra 'Rowher' (Black Walnut) · J. nigra 'Sauber 1' (Black Walnut) · J. nigra 'Schrieber' (Black Walnut) · J. nigra 'Sparrow' (Black Walnut) · J. nigra 'Surprise' (Black Walnut) · J. nigra 'Thomas Black' (Black Walnut) · J. nigra 'Thomas Myers' (Black Walnut) · J. regia (Carpathian Walnut) · J. regia var. Carpathian (Carpathian Walnut) · J. regia 'Allegheny' (Carpathian Walnut) · J. regia 'Bedco 1' (Carpathian Walnut) · J. regia 'Broadview' (Dwarf English Walnut) · J. regia 'Cascade' (Carpathian Walnut) · J. regia 'Champion' (Carpathian Walnut) · J. regia 'China-B' (Carpathian Walnut) · J. regia 'Coble #2' (Carpathian Walnut) · J. regia 'Colby' (Carpathian Walnut) · J. regia 'Greenhaven' (Carpathian Walnut) · J. regia 'Hansen' (Carpathian Walnut) · J. regia 'Kaiser' (Carpathian Walnut) · J. regia 'Ky Giant' (Carpathian Walnut) · J. regia 'Lake' (Carpathian Walnut) · J. regia 'Looking Glass' (Carpathian Walnut) · J. regia 'Mckinster' (Carpathian Walnut) · J. regia 'Northern Prize' (Carpathian Walnut) · J. regia 'Perry' (Carpathian Walnut) · J. regia 'Purpurea' (Carpathian Walnut) · J. regia 'Reda' (Carpathian Walnut) · J. regia 'S-1' (Carpathian Walnut) · J. regia 'Shiawassee' (Carpathian Walnut) · J. regia 'Somers' (Carpathian Walnut) · J. regia 'Utah Giant' (Carpathian Walnut) · J. × bixbyi (Bixby Walnut) · J. x intermedia (Intermediate Walnut) · J. 'Royal' (Walnut)

More Info

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal February 01, 2008:

Identifiers

Footnotes

  1. Anmin Lu, Donald E. Stone & L. J. Grauke "Juglandaceae". in Flora of China Vol. 4 Page 277. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org. [back]
  2. Alan T. Whittemore & Donald E. Stone "Juglans". in Flora of North America Vol. 3. Oxford University Press. Online at EFloras.org. [back]
  3. "Juglans microcarpa". in Flora of North America Vol. 3. Oxford University Press. Online at EFloras.org. [back]
  4. Mean = 736.770 meters (2,417.224 feet), Standard Deviation = 501.580 based on 70 observations. Altitude information for each observation from British Oceanographic Data Centre. [back]
Last Revised: 7/15/2012