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Pinus clausa

Pinus clausa
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Scientific name: Pinus clausa  (Chapman ex Engelmann) Vasey ex Sargent  1884

Synonyms: Pinus clausa subsp. immuginata (D.B.Ward) A.E.Murray, Pinus clausa var. immuginata D.B.Ward, Pinus inops var. clausa Chapm. ex Engelm., Pinus inops subsp. clausa (Chapm. ex Engelm.) Engelm., Pinus virginiana subsp. clausa (Chapm. ex Engelm.) Eckenw.     

Common names: Sand pine, Florida spruce pine

 

Description

Trees to 21 m tall, trunk to 0.5 m d.b.h., often stunted and crooked, branching low or sometimes multi-stemmed. Crown open and irregular or flattened. Bark scaly, breaking into narrow ridges and furrows, grey-brown, in the crown thin and flaking, red-brown. Shoots slender, purplish to reddish brown, often glaucous, glabrous, rough with persistent pulvini after leaf fascicles have fallen. Buds ovoid to cylindrical, 0.5-1 cm long, with or without resin, red-brown; cataphylls with white, fringed margins. Leaves in fascicles of 2, held in 4-8 mm long sheaths, persisting 3-4 years, spreading, (2-)5-8(-10) cm long, nearly straight or contorted, 1-1.5 mm wide, rigid, dark green or light green; margins minutely serrulate; apex acute; stomata in inconspicuous lines on all surfaces. Pollen cones in small clusters, spirally arranged, short cylindric, 10-15 mm long, yellow maturing to red-brown. Seed cones solitary or in pairs, persistent, nearly sessile or short pedunculate, serotinous or opening soon in warm sunshine, symmetrical, 4-8 cm long, narrowly ovoid when closed, broadly ovoid when open. Seed scales thin woody, rigid, often purple on the border below the apohysis on adaxial surface, turning brown when old. Apohysis slightly raised, keeled, angular in outline, with a small, low pyramidal umbo terminating in a small prickle or unarmed, colour dull reddish brown when cones are ripened. Seeds obovoid, slightly flattened, 4-6 mm long, pale brown with darker spots or dark brown, with a narrow wing 15-20 mm long.

Southern portion of the range of the species in Florida and adjacent coastal Alabama. Confined to sand hills and dunes at up to 60 m, the highest elevation within its range; 0-60(-90) m.

 

Conservation Status

Red List Category & Criteria: Least Concern

Pinus clausa is a widespread and common species that is not being exploited on a large scale and shows no signs of decline: it may even be increasing where other land uses are retreating as on marginal farmland. It is therefore assessed as Least Concern.

This lowland pine from the sandy interior and coasts of Florida occupies the drier areas away from swamps and eutrophic rivers. It is a fire-successional species, in particular on infertile white sand dunes and flats of marine origin and low elevations between 5 and 60 m a.s.l. or up to 90 m on the west coast. There are abundant summer rains while winters are generally dry, but much of the precipitation drains away quickly into the sandy soil. There are two ecotypes or 'races' of this species, one with mostly serotinous cones and another of which the cones open more readily; these were recognized previously as botanical varieties. Pinus clausa is characteristic of 'sand pine scrub' a distinctive plant community of north-central Florida. The tree layer is dominated by Pinus clausa, with an understorey composed of evergreen shrubs to 3 m tall and in almost total absence of a herb layer. Several species of oak (Quercus) and small palms (Sabal etonia, Serenoa repens) are most abundant. The ground is often covered by lichens (Cladina evansii, Cladonia spp.).

Sand pine is of some value as a timber tree only in plantations, where it can give a reasonably high yield for the pulp wood industry. The 'Chocktawhatchee' form of western Florida with short branches and dark green needles is grown as a Christmas tree. The species is thought to be of use in 'biomass plantations' for fuelwood from trials conducted by the USDA Forest Service in the 1980's. Such use may become more important in the current political drive to reduce dependence on oil in the US and to increase the contribution of 'renewables' to the fuel for motorcars. This species has no significance in horticulture.

This species is recorded from several protected areas within its range.

 

References

  • Farjon, A. (2010). A Handbook of the World's Conifers. Koninklijke Brill, Leiden.
  • Eckenwalder, J.E. (2009) Conifers of the World: The Complete Reference. Timber Press, Portland.
  • IUCN Red List of Threatened Species, International Union for Conservation of Nature and Natural Resources. Cambridge, UK /Gland, Switzerland

Copyright © Aljos Farjon, James E. Eckenwalder, IUCN, Conifers Garden. All rights reserved.


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