Rhynchospora vernalis E. Bridges & Orzell, 2023

Rhynchospora vernalis E. Bridges & Orzell View in CoL , sp. nov. ( Fig. 9 View FIG ). TYPE: U.S. A. FLORIDA:Highlands Co.: wet prairie margin of cypress dome with short-stature Taxodium ascendens just N of Kissimmee Rd, ca. 0.7mi E of O.Q.Rd at O.Q. Range; Avon Park Air Force Range; Lake Arbuckle NE 7.5'Quad.; SEQ, SWQ Sec.4, T33S, R30E; 27°37'55"N; 81°19' 44"W; 18 Apr 1998, Orzell and Bridges 25273 [HOLOTYPE: NCU; ISOTYPES: DUKE, FLAS,FSU, FTU, GA,MO,NCSC, NY, USF].

Diagnosis.— Similar to Rhynchospora microcarpa , differing in being more robust,with widely spreading primary inflorescence branches, lighter brown spikelets,and with unequal bristle lengths from 0.9–1.5 times as long as the achene body.

Description.— Densely cespitose perennial, typically with 8–18(–26) culms per clump. Largest culms in each clump mostly 1.2–1.4(–1.7) m tall, with shorter culms in the clumps 0.4–1.0 m tall, each culm with (3–)7–12(– 21) basally disposed leaves. Leaves (11–)40–60(–88) cm long, (2–)3–5(–7) mm wide, glabrous. Inflorescence (11–)20–32(–50) cm long, typically occupying only the terminal 20–30% of the culm length. Inflorescence units (clusters) mostly 2–3(–5) per culm, 3–5(–6) cm wide, (3–)5–8(–12) cm long, subtended by a leaf-like bract mostly 2–5(–8) cm long and 1–2 mm wide, the primary branches of each unit spreading to ascending in flower, not flexuous, becoming ascending in fruit, each unit rather open and diffuse (not congested) with elongate primary branches, the terminal branchlets mostly separated, each with a terminal cluster of 3–8 well-defined spikelets, not closely packed, the lowermost spikelets in each cluster pedicellate. Spikelets light to medium brown (not dark brown), broadly ovoid, 2–3.5 mm long, 2–3 mm wide, often 3–5 or more fruited, spikelet scales broadly ovate, abruptly short-aristate. Achenes broadly obovoid, biconvex, but not strongly tumid, light to medium brown (not dark brown), 1.0– 1.2 mm long, 0.8–1.1 mm wide, the length/width ratio mostly 1.0–1.2. Achene surface strongly transversely ridged, with 6–8 mostly irregular ridges, the alveolae very narrow. Bristles 6, sometimes easily detached, finely antrorsely barbed, 0.9–1.6 mm long, unequal in length, from 0.9–1.5 times as long as the achene body, the shortest slightly shorter than the achene body, the longest nearly as long as the tubercle. Tubercle broadly conic to deltoid, narrower than the top of the achene body, 0.4–0.5 mm wide at the base, 0.4–0.5 mm long, distinct from the achene body and not decurrent on the achene, the margins smooth (not setose). See Figs. 10–13 View FIGS .

In Flora of North America, Volume 23, page 228, Kral (2002), in his discussion of Rhynchospora microcarpa , states “In peninsular Florida, apparent intergradation with R. elliottii produces some individuals with broad leaves and triangular subulate tubercles on nearly flat fruits.” McMillan (2007) notes that, as expected, some characters overlap between the closely related species of this section, but that these do not show a pattern which would indicate intergradation between species. This manuscript further clarifies these issues, since some of the confusion between R. microcarpa and R. elliottii for specimens now referred to R. vernalis is borne out by annotation labels in which experts shift determinations back and forth between these two species.

Writing a consistently workable key to Rhynchospora sect. Globulares and Mixtae has been a challenge for many authors. In Weakley & Southeastern Flora Team (2022a), LeBlond combines these two sections into a single long key with several of the species (notably, R. microcarpa , R. decurrens , and R. sulcata ) keying out in multiple couplets, based on subtle differences in achene thickness (expressed as having either tumid, biconvex, concave-convex, flattened or concave achene faces) and bristle length, which can vary between species in these sections from being absent or nearly so to consistently exceeding the tubercle length. However, in each of these key locations, R. vernalis will key out imperfectly at the couplets separating R. decurrens , R. microcarpa and R.sulcata . The couplets from the key below separating these can be inserted in the Weakley& Southeastern Flora Team (2022a) key and will likely work in identifying R. vernalis . The following key is based on the Rhynchospora key in McMillan (2006, 2007), for sect. Mixtae.