Cladrastis kentukea
Kentucky yellowwood flowers
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Fabales
Family: Fabaceae
Subfamily: Faboideae
Genus: Cladrastis
Species:
C. kentukea
Binomial name
Cladrastis kentukea
(Dum.Cours.) Rudd (1971)
Natural range of Cladrastis kentukea
Close-up of natural range of Cladrastis kentukea
Synonyms[2]
  • Cladrastis albiflora Raf.
  • Cladrastis fragrans Raf.
  • Cladrastis kentuckensis (Dum.Cours.) Jacks.
  • Cladrastis kentuckensis Raf.
  • Cladrastis kentuckensis Raf. ex B.D. Jacks.
  • Cladrastis lutea (Michx.) K.Koch
  • Cladrastis lutea Raf.
  • Cladrastis tinctoria Raf.
  • Sophora kentukea Dum.Cours.
  • Virgilia alba Raf.
  • Virgilia kentuckensis Raf.
  • Virgilia lutea Michx.

Cladrastis kentukea, the Kentucky yellowwood or American yellowwood (syn. C. lutea, C. tinctoria), is a species of Cladrastis native to the Southeastern United States, with a restricted range from western North Carolina west to eastern Oklahoma, and from southern Missouri and Indiana south to central Alabama. The tree is sometimes also called Virgilia.[3]

Description

Leaves

Cladrastis kentukea is a small to medium-sized deciduous tree typically growing 10–15 metres (33–49 ft) tall, exceptionally to 27 metres (89 ft) tall, with a broad, rounded crown and smooth gray bark. The leaves are compound pinnate, 20–30 cm long, with 5-11 (mostly 7-9) alternately arranged leaflets; each leaflet broad ovate with an acute apex; 6–13 cm long and 3–7 cm broad, with an entire margin and a thinly to densely hairy underside. In the fall, the leaves turn a mix of yellow, gold, and orange.

The flowers are fragrant, white, produced in Wisteria-like racemes 15–30 cm long. Flowering is in early summer (June in its native region), and is variable from year to year, with heavy flowering every second or third year. The fruit is a pod 5–8 cm long, containing 2-6 seeds.

  • Bark: Smooth gray, or light brown. Branchlets at first downy, but soon become smooth, light yellowish green; later red brown, finally dark brown.
  • Wood: Yellow to pale brown; heavy, hard, close-grained and strong. Sp. gr., 0.6278; weight of cu. ft., 39.12 lbs.
  • Winter buds: Four in a group, making a tiny cone and enclosed in the hollow base of the petiole.
  • Leaves: Alternate, pinnately compound, eight to twelve inches long, main stem stout, enlarged at base. Leaflets seven to eleven, broadly oval, three to four inches long. Wedge-shaped at base, entire, acute, terminal leaflets rhomboid-ovate. Feather-veined, midrib and primary veins prominent, grooved above, light yellow beneath. They come out the bud pale green, downy; when full grown are dark green above, pale beneath. In autumn they turn a bright clear yellow.
  • Flowers: June. Perfect, papilionaceous, white, borne in drooping terminal panicles twelve to fourteen inches long, five to six inches broad, slightly fragrant.
  • Calyx: Campanulate, five-lobed, enlarged on the upper side.
  • Corolla: Papilionaceous; standard broad, white, marked on the inner surface with a pale yellow blotch; wings oblong; keel petals free.
  • Stamens: Ten, free; filaments thread-like.
  • Pistil: Ovary superior, linear, bright red, hairy, bearing a long incurved style.
  • Fruit: Legume, smooth, linear-compressed, tipped with the remnants of the styles. Seeds four to six, dark brown.[3]

Distribution

One of the rarest trees of eastern North America.[4] Found principally on the limestone cliffs of Kentucky, Tennessee and North Carolina, but it is hardy at the north to zone 4.

The largest specimen known is at Spring Grove Cemetery in Cincinnati, Ohio, 22 m tall and 2.2 m trunk diameter; the tallest known is a slender tree 27 m tall but only 0.55 m trunk diameter, at Plott Cove Research Natural Area, Georgia (Spongberg & Ma 1997; Eastern Native Trees Society).

Plants from Alabama have the leaves more densely hairy underneath than those from further north, and are distinguished as Cladrastis kentukea f. tomentosa (Steyermark) Spongberg.

Cultivation

Cladrastis kentukea is widely grown as an ornamental tree for its attractive flowers, and is locally naturalized in many areas of the eastern United States outside of its restricted native range.[3] It thrives in full sunlight and in well-drained soil, tolerates high pH soils as well as acid situations. The Yellowwood can withstand urban settings and is attractive to birds. A number of cultivars have been selected, including 'Perkin's Pink' (syn. 'Rosea', an invalid name) with pink flowers.

Kentucky yellowwood is recommended as one of the best medium-sized trees for cultivation as an ornamental plant in gardens. The only quality that is mentioned is a tendency of the trunk to divide very near the ground, as a multi-trunked tree.[3]

bark and low branching habit

Uses

The name yellowwood derives from its yellow heartwood, used in small amounts for specialist furniture, gunstocks and decorative woodturning.

This plant has been marked as a pollinator plant, supporting and attracting bees and butterflies.[5]

Distinctions

Yellowwood won a Pennsylvania Horticultural Society Gold Award in 1994.[6]

The Society of Municipal Arborists selected the yellowwood (Cladrastis kentukea or C. lutea) as its Urban Tree of the Year for 2015.

References

  • Andrews, S. Trees of the Year: Cladrastis and Maakia. Int. Dendrol. Soc. Year Book 1996: 12–26.
  • Spongberg, S. A. & Ma, J.-S. (1997). Cladrastis (Leguminosae subfamily Faboideae tribe Sophoreae): a historic and taxonomic overview. Int. Dendrol. Soc. Year Book 1996: 27–35.
  1. ↑ IUCN SSC Global Tree Specialist Group & Botanic Gardens Conservation International (BGCI) (2020). "Cladrastis kentukea". IUCN Red List of Threatened Species. 2020: e.T153739999A181463533. doi:10.2305/IUCN.UK.2020-3.RLTS.T153739999A181463533.en. Retrieved 11 October 2022.
  2. ↑ "The Plant List: A Working List of All Plant Species". Retrieved 27 March 2015.
  3. 1 2 3 4 Keeler, Harriet L. (1900). Our Native Trees and How to Identify Them. New York: Charles ScribNer's Sons. pp. 116–118.
  4. ↑ Chen, Kevin (December 19, 2017). "Yellowwood (Cladrastis kentukea) | University of Minnesota Urban Forestry and Research: The UFOR Nursery & Lab". trees.umn.edu. Retrieved 2023-05-09.
  5. ↑ "Planting Guides" (PDF). Pollinator.org. Retrieved 2022-01-29.
  6. ↑ "Yellowwood Tree Profile". UK Department of Horticulture. Kentucky Cooperative Extension. Retrieved 11 June 2019.
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