Laguncularia racemosa |
Combretaceae |
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white mangrove |
white mangrove family |
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Habit | Shrubs or trees to 10(–20) m. Leaves: petiole 6–15 mm; blade ovate to obovate, oblong, or suborbiculate, 2–9.7 × 1.4–5 cm, base obtuse to rounded, folded longitudinally when young, with a faint longitudinal line each side of midvein in age. | Trees, shrubs, or lianas, monoecious, dioecious, or polygamous, terrestrial, amphibious, or aquatic, sometimes with erect, monopodial trunk supporting a series of horizontal, sympodial branches, armed or unarmed, not clonal; mucilaginous cells or canals often present in parenchymatous tissues; hairs various, some long, straight, sharp-pointed, eglandular, unicellular, and very thick-walled, with conic internal compartment at base (combretaceous), sometimes hairs also short-stipitate, glandular; roots occasionally with pneumatophores. | ||||||||||||||||
Stems | erect, horizontal, spreading, or prostrate; bud scales absent. |
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Leaves | persistent or deciduous, alternate and spiral, or opposite or subopposite and decussate, simple; stipules usually absent, sometimes present and minute; petiolate, petiole or base of blade often with 2 circular to elliptic and flat structures or flask-shaped nectariferous cavities; blade papery to leathery, venation pinnate, secondary veins often forming loops or smoothly arching toward margin, margins entire, surfaces glabrous or hairy; domatia often present as pits, pouches, or hair tufts. |
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Inflorescences | terminal and/or axillary, spikes or panicles [racemes]; bracts present (each flower in axil of a usually caducous bract); bracteoles 0 or 2, adnate to hypanthium. |
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Spikes | (or spicate units of panicles), 2–13 cm. |
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Flowers | sepals 1 mm; stamens 1.5–2 mm; style 1–2 mm. |
bisexual or unisexual, staminate and pistillate on same or different plants, or bisexual and staminate on different plants, or all bisexual, usually actinomorphic; perianth and androecium borne on hypanthium; hypanthium cupulate, cylindric, or tubular, slightly to conspicuously prolonged beyond ovary and differentiated into 2 parts—proximally adnate to ovary, distally free; sepals 4 or 5, distinct or connate basally, imbricate to valvate; petals (0[4] or)5, distinct, imbricate or valvate; nectary present, usually a lobed or unlobed disc on top of ovary, often hairy; stamens [4 or]5–10[–16], inflexed in bud; filaments distinct, included to long-exserted; anthers dorsifixed, dehiscent by 2 longitudinal slits; pollen grains 3-colporate, often also with poreless furrows; pistil 2–5-carpellate, carpels connate; ovary inferior [semi-inferior], 1-locular; placentation apical; style 1; stigma 1, punctate to capitate; ovules 2–5[or 6], pendulous on elongate funiculi from apex of locule, anatropous, bitegmic, crassinucellate. |
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Fruits | drupes, ribbed and/or winged, dry to spongy or fleshy. |
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Drupes | greenish or gray-green [reddish green], 13–20 × 5–9 mm, pubescent [glabrous]. |
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Seed | 1 per fruit, relatively large, outer portion of seed coat fibrous; embryo with usually 2 folded or spirally twisted cotyledons; endosperm absent. |
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Laguncularia racemosa |
Combretaceae |
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Phenology | Flowering spring–early summer. | |||||||||||||||||
Habitat | Tidal swamps, mangrove communities. | |||||||||||||||||
Elevation | 0 m. (0 ft.) | |||||||||||||||||
Distribution |
FL; TX; e Mexico; Central America; South America; West Indies; w Africa
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e Mexico; Central America; South America; s United States; West Indies; Asia; Africa; Australia; pantropical; warm temperate areas |
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Discussion | Laguncularia racemosa is an important component of mangrove swamps in central and southern Florida (extending northward to Levy County on the Gulf Coast and to Volusia County on the Atlantic Coast); it also recently has been reported from Willacy County, Texas. The species is occasionally cultivated as an ornamental tree or shrub in coastal situations. The flowers are quite fragrant and are pollinated by bees. The fruits are semiviviparous, the green embryo piercing the seed coat while the fruit is still on the tree. Some populations have some plants with bisexual flowers and others with staminate flowers, while in others all flowers are bisexual. The frequency of staminate plants in Florida is variable (0–68%). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Genera 11, species ca. 500 (5 genera, 8 species in the flora). Combretaceae are clearly placed within Myrtales, a major angiosperm order whose monophyly is well supported by anatomy, embryology, and morphology (L. A. S. Johnson and B. G. Briggs 1984), as well as by plastid and nuclear DNA sequences (M. W. Chase et al. 1993; E. Conti et al. 1996, 1997; V. Savolainen et al. 2000, 2000b; D. E. Soltis et al. 2000, 2001; K. W. Hilu et al. 2003; Wang H. et al. 2009; O. Maurin et al. 2010, 2017). Morphological characteristics of Combretaceae supporting this placement include vessel elements with vestured pits, stems with internal phloem, stipules absent or present as very small lateral structures, flowers each with a short to elongate hypanthium, stamens incurved in bud, and a single style (W. S. Judd et al. 2008). C. A. Stace (2007) recognized two subfamilies within Combretaceae: Strephonematoideae Engler & Diels (only Strephonema Hooker f. of western tropical Africa) and Combretoideae Burnett (all remaining genera); DNA-based phylogenetic analyses have supported this distinction (Tan F. X. et al. 2001, 2002; O. Maurin et al. 2010). Within the latter subfamily, two tribes are distinguished: Laguncularieae Engler & Diels (Dansiea Byrnes, Laguncularia, Lumnitzera, Macropteranthes F. Mueller) and Combreteae de Candolle [Combretum, Conocarpus, Finetia Gagnepain, Getonia Roxburgh, Guiera Adanson ex Jussieu, Terminalia]. Phylogenetic relationships within the family are imperfectly understood, and problems of generic circumscription exist (Stace). Combretaceae are distributed pantropically, with extensions into warm temperate regions; within the geographical coverage of this flora, the species here treated are usually considered to be restricted to Florida; however, Conocarpus erectus and Laguncularia racemosa likely have become established on South Padre Island (Willacy County), Texas (B. L. Turner et al. 2003; Texas Non-Native Plants Group, http://www.texasnonnatives.org). The family is ecologically significant in coastal regions of southern and central Florida due to the presence of the mangrove species Laguncularia racemosa and the mangrove-associate C. erectus. Both occur in extensive coastal stands [along with Avicennia germinans and Rhizophora mangle]. Lumnitzera racemosa is also a mangrove species; it occurs in southern Florida only in a single naturalized population and shows potential to be an invasive species (J. W. Fourqurean et al. 2010). Combretum indicum, Terminalia catappa, T. muelleri, and, probably, T. buceras are also non-native; only the first two are considered invasive. Fruit dispersal in Conocarpus, Laguncularia, and Lumnitzera is by floating in water; the fruits of Terminalia are eaten by mammals and birds; they float and may be secondarily water-dispersed. Combretaceae are not of great economic importance, although Terminalia buceras, T. catappa, and T. molinetii are widely used as shade trees and/or ornamentals in southern Florida due to their distinctive growth architecture, and cultivars of Conocarpus erectus with densely pubescent leaves are widely used as ornamental shrubs or small trees because of their distinctive coloration and salt tolerance. Terminalia catappa has fruits with edible kernels. Combretum indicum is often grown as an ornamental vine because of its showy flowers, which open white and change to pink and then red as the day progresses. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 10. | FNA vol. 10. | ||||||||||||||||
Parent taxa | Combretaceae > Laguncularia | |||||||||||||||||
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Synonyms | Conocarpus racemosus | |||||||||||||||||
Name authority | (Linnaeus) C. F. Gaertner: Suppl. Carp., 209. (1807) | R. Brown | ||||||||||||||||
Web links |