Rhynchospora floridensis (Britton ex Small) H.Pfeiff.
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Authority
Thomas, William W. 1984. The systematics of Rhynchospora section Dichromena. Mem. New York Bot. Gard. 37: 1-116.
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Family
Cyperaceae
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Scientific Name
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Description
Species Description - Cespitose, mostly glabrous, perennial; culms erect, 17-45 cm tall, 0.5-0.9 mm in diameter, obtusely triquetrous, green, rarely swollen basally; leaves mostly basal, usually only 2 cauline, filiform to plicate or flat; basal leaves 15-40 cm long, 0.42 mm wide, uppermost leaves of fertile culms with blades 10-13 cm long, 1-1.5 mm wide, occasionally pale at base; sheaths of uppermost leaves 3.5-4.5 cm long, green; summit of inner band concave, hyaline only at summit; inflorescence bracts green distally, white basally both adaxially and abaxially, 3-6 exceeding inflorescence, often sparsely ciliate basally along margins; basal bract longest, 5-17 cm long, 1.5-4 mm wide; white portion 0.6-2 cm long; inflorescence a congested, obconic to hemispherical head of 4-9 spikelets; spikelets ovoid, 4-6.5 mm long, 1.2-2.2 mm wide, consisting of 10-20 scales; scales creamy white distally, ferrugineously streaked basally, 3.1-3.8 mm long, 2-3 mm wide, ovate, cymbiform, apex rounded; basal scales carinate distally, ciliolate along keel; filaments 3.1-4 mm long; anthers 1.9 mm long; stigma and style 2.1-3.3 mm long; stigma branches 1.2-2.1 mm long; achene (Fig. 7c) lenticular, bilaterally symmetrical, stramineous to orangish-brown when young becoming black or dark brown when mature, usually somewhat longer than wide, 0.9-1.2 mm long, 0.9-1 mm wide; summit of achene horizontal; shoulders of achene at edge of style base confluent with achene margin; style base 0.3-0.5 mm high, 0.6-0.8 mm broad at base, grey to greyish brown, shallowly triangular to triangular; achene surface transversely ru-gulose; epidermal cells of achene narrowly elliptic, indistinct. Flowering and Fruiting: Mature flowering and fruiting specimens have been collected throughout the year. Distinguishing Features: Rhynchospora floridensis is cespitose, with bracts which are white adaxially and abaxially, and bract margins and spikelet scale keels which are ciliolate basally. The achenes are usually quite dark and elliptic rather than obovate. The specimens from Chiapas are distinct in that the bases of the culms are somewhat swollen and bulbous.
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Discussion
Type: Florida, Dade Co., Coconut Grove, Small & Nash 181 (NY, holotype; NY, US-2, F, isotypes; NY, photograph of holotype). Dichromena floridensis C. B. Clarke, Kew Bull. Add. Ser. 8: 32. 1908. Rhynchospora stellata forma floridensis (Britton ex Small) Kükenthal, Bot. Jahrb. Syst. 75: 300. 1951. Dichromena inaguensis Britton in Britton and Millspaugh, Bahama Flora 53. 1920. Type: Bahamas, Little Inagua, 21 Oct 1904, Nash & Taylor 1254 (NY, holotype; US, isotype; NY, photograph of holotype). Pollination: Although I did not have an opportunity to observe insects visiting R. floridensis, its similarity to other insect-pollinated species such as R. latifolia and R. colorata leads me to believe that it is also insect pollinated. Nomenclature: This species is often cited as having been first described by C. B. Clarke in 1908, although it was described by Small five years earlier. Clarke gave it the same name and cited the same type. Since it has the same type, it is not a homonym (Art. 64, Stafleu et al., 1978) but should be considered an “iso-nym (Nicolson, 1975). Kükenthal’s use of Clarke as the original author should be considered as a bibliographic error to be replaced by “Britton ex Small.” The description is probably Small’s using Britton’s name rather than Britton’s description used by Small. Thus the authority should be “Britton ex Small” rather than “Britton in Small.” The description is in Small’s style and Britton indicated a previous lack of familiarity with the species by describing it as new in 1920.
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Distribution
Habitat: Rhynchospora floridensis occurs in open pine woods with very shallow soil over limestone. In Florida the limestone is a type known as Miami oolite, found south of the Tamiami Trail and in the larger Keys (Long and Lakela, 1971). According to Lundell (1934) the soils of the Yucatán Peninsula are also shallow and underlain by limestone, providing a habitat similar to that in southern Florida. Similar conditions exist in the Bahamas as well (Britton and Millspaugh, 1920).
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