Chamaecrista horizontalis A.R.Franck, 2021

Weakley, Alan S., Poindexter, Derick B., Medford, Hannah C., Franck, Alan R., Bradley, Keith A., Sadle, Jimi & Kelley, John Michael, 2021, Studies In The Vascular Flora Of The Southeastern United States. Vii, Journal of the Botanical Research Institute of Texas 15 (1), pp. 23-56 : 48-49

Chamaecrista horizontalis A.R.Franck , sp. nov. ( Figs. 13B, 13D , 14 ). TYPE: U.S.A. GEORGIA. Taylor Co.: 3mi N of Butler , 18 Jul 1948, Cronquist 5516 (HOLOTYPE: GA039438 ; ISOTYPES: FLAS51702 , GH01873982 , IND0049273 , LSU0067554 , NY01453567 , US 00366391) .

Diagnosis.— Chamaecrista horizontalis is placed in Chamaecrista ser. Chamaecrista owing to its pinnately veined leaflets, supra-axillary inflorescence arising along the stem between two leaf nodes whereby the peduncle is adnate to the stem internode, and sepals with inconspicuous venation. Within this series, C. horizontalis is distinguished by its perennial and horizontal main root to 46+ cm long, usually several erect main stems mostly narrower than the horizontal root, leaves usually with 8 or more leaflets,relatively large flowers over 1 cm wide,and yellow to yellow-brown anthers.

Description.— Plant perennial, herbaceous, 30–60 cm tall. Primary root generally horizontal, 2–7 mm wide, to 46+ cm long, with scattered finer roots. Stems erect to erect-ascending, unbranched or basally few-branched, straight to slightly zigzagged, sometimes curved near the base, terete to slightly ridged, the ridges decurrent from the petiole and stipules, glabrous to puberulent, 1–2.3 mm wide, often clustered along the primary root or in fascicles of up to 12 stems, the fascicle sometimes on a short stipe, stipe to 5 mm wide, to 16 mm long. Stipules lanceolate-subulate, (2–) 3.6–8 mm long, 0.6–2 mm wide, smaller towards the base of the plant. Leaves alternate, paripinnate, (2–)16–34-foliolate, the leaflets opposite, leaves in proximal third of the stem typically with fewer leaflets, the basal-most leaf as few as 2-foliolate, rachis (0–) 1.6–3.9 cm long, ca. 0.5 mm wide, petiole glabrous to puberulent, 2–5 mm long, ca. 0.5 mm wide, subtended by the 1–2 mm long pulvinus, petiolar gland near or at mid-petiole, sessile, discoid to ellipsoid, to 1 mm wide, to 1 mm long. Leaflets oblongelliptic, glabrous, (5.5–) 8–18 mm long, 1.8–5 mm wide, asymmetric, the portion of the blade on the proximal side of the midrib up to twice as wide as the distal side, usually awned at the apex, the awn to 1 mm long, the midrib abaxially pronounced and prominulous, with 4–11 lateral veins, the veins adaxially obscure, abaxially obscure to pronounced and prominulous, pulvinuli ca. 0.5 mm long, 0.5–0.8 mm wide. Inflorescence solitary or in fascicles of 2, arising from the stem 2–6 mm above the subtending leaf (the peduncle adnate to the stem), with a solitary flower. Pedicel glabrous to puberulent, 12–19 mm long, ca. 0.5 mm wide, slightly thicker in fruit, subtended by two bracts attached to the stem, 5 mm long, 1.3 mm wide, with two bracteoles above the middle, 2.9–4 mm long, 0.9–1.1 mm wide. Sepals 5, lanceolate-subulate, glabrous or medially sparingly puberulent abaxially, 11.7–14 mm long, 1.6–2.4 mm wide. Petals 5, yellow, sometimes with a red spot at the base, obovate, the two apical petals 11–15 mm long, 5–7.5 mm wide, the two lateral petals 15–19 mm long, 6–9 mm wide, the basal petal 15–19 mm long, 10–15 mm wide. Anthers 10, yellow to yellow-brown, straight to arcuate, 6.5–11 mm long, the filament ca. 1 mm long. Style yellow, incurved, 8–12 mm long. Fruit linearrhomboid, glabrous to puberulent, dehiscent, with 7–12 partitions, 4.2–5.3 cm long, 0.4–0.6 cm wide. Seed not observed.

Chamaecrista horizontalis is known from the pinelands and oak woodlands of southern Alabama, southwestern Georgia, southeastern Mississippi, and the western Florida panhandle. Plants have yellow to yellow-brown anthers, as apparent from specimen labels, recent herbarium specimens, and live plants (Keener et al. 2021). The horizontal roots of C. horizontalis probably can exceed 46 cm long, as the longest on herbarium specimens (e.g., Davis 16081, FLAS and Adams & Tyson 838, FSU) appear to be cut or broken. Further, Pullen (1963: 23) was presumably referring to this species when he stated that clones of up to four meters in diameter have been observed.

In 1948, Cronquist collected plants of C. horizontalis in Taylor County, Georgia, and applied the name C. deeringiana since he thought his plants were “clearly identical with the [southern] Florida plant” ( Cronquist 1949). In March 1962, Erdman West added an annotation on Godfrey 61238 (FLAS) that reads, “A perennial rhizomatous form from West Florida for which we have not yet found a name.” In agreement with Cronquist (1949), Pullen (1963) applied the name C. deeringiana in the wide sense to include those plants here called C. horizontalis .

Later authors continued applying the name C. deeringiana to perennial plants in Alabama, Georgia, Mississippi, and the Florida panhandle (Pullen 1963; Irwin & Barneby 1982; Isely 1975, 1998; Chafin 2007; Weakley 2020; Keener et al. 2021). Isely (1975, 1998) did not include Alabama, Georgia, or Mississippi in the range of C. horizontalis (using the misapplied name C. deeringiana ), although he annotated some Georgia specimens as C. deeringiana (e.g., Buckner s.n., GA and Duncan & Hardin 13615, GA).

The yellow to yellow-brown anthers of C. horizontalis distinguish it from C. deeringiana with its dark red to purple-red anthers (sometimes yellow towards the base). Herbarium specimens suggest that the horizontal roots of C. horizontalis are longer than those of C. deeringiana , which could be a consequence of their differing habitats. A common garden experiment would probably be necessary to determine if their root lengths actually differ.Flowering time appears to be restricted to late May to early August in C. horizontalis , while C. deeringiana can flower year-round in Miami-Dade County, Florida, where freezing temperatures usually do not occur.

Specimens examined: U.S. A. ALABAMA. Baldwin Co.: 6.9 mi NE of Bay Minette, 2 Jun 1970, Kral 39533 ( GH); W of route 112, 1.1 mi N of jct. with C-64, 22 Jun 1997, Sorrie 9327 ( NCU) . Conecuh Co.: US 31, E side of Sepulga River , 4 Jul 2013, Diamond 24306 ( TROY, UWAL) . Covington Co.: 15 Jun 1999, MacDonald 13023 ( MISSA, TROY) ; 4.5 mi E of Florala , 8 Jul 1999, Stewart & MacDonald 6741 ( DSC) ; Crooked Road , 20 May 2011, Diamond 22135 ( TROY, UWAL) . Crenshaw Co.: 4 Sep 1997, Diamond 11115 ( AUA) . Escambia Co.: 8.8 air mi NW of Flomaton , 21 Jun 2007, Schotz 2061 ( UNA) . Geneva Co.: Geneva State Forest , 15 Jun 1999, MacDonald & Warren ( DUKE) . Houston Co.: 29 May 1999, MacDonald 12901 ( TROY) . Pike Co.: 17 Jun 2016, Diamond 27488 ( TROY) . FLORIDA. Calhoun Co.: 0.75 mi S of Clarksville , 20 Jul 1954, Ford 3398 ( FLAS) ; 4.5 mi NW of Clarksville , 31 Jul 1957, Ford 5006 ( FLAS) . Liberty Co.: near Bristol , 22 Jul 1940, West & Arnold s.n. ( FLAS) . Okaloosa Co.: 2 mi W of Laurel Hill , 2 Aug 1961, Godfrey 61297 ( FSU) ; 3.5 mi SW of Laurel Hill , 2 Aug 1961, Godfrey 61309 ( FSU) ; ibid., Godfrey 61331 ( FSU, USF) . Santa Rosa Co.: 15 mi SE of Milton , 30 May 1967, Smith 1360 ( FLAS) ; 11 mi N of Holley , 21 Jun 1967, Smith 1538 ( FLAS) . Walton Co.: 10 mi S of DeFuniak Springs , 3 Jun 1954, West & Arnold s.n. ( FLAS) ; Eglin Air Force Reservation , 13 Sep 1955, West s.n. ( FLAS) ; vicinity of Buffalo Lake , N of DeFuniak Springs, 2 Aug 1961, Godfrey 61238 ( FLAS, FSU, GH, US, USF) ; 4 mi S of Freeport , 7 Aug 1972, Davis 16074 ( CM, FLAS [2 sheets]) ; ibid., 25 Aug 1972, Davis 16081 ( FLAS) ; ibid., 14 Aug 1977, Ward 9205 ( FLAS [2 sheets]) ; ibid., 31 Aug 1982, Davis & Davis s.n. ( FSU) . Washington Co.: post office of Crystal Lake , 29 Jul 1954, Ford 3739 ( FLAS) ; 24 Jun 1961, Adams & Tyson 838 ( FSU [2 sheets], UWFP) . GEORGIA. Decatur Co.: 12 mi W of Bainbridge , 10 Jun 1966, Buckner s.n. ( GA, LSU) . Mitchell Co.: 3.2 air mi NW of Bridgeboro , 17 Jul 2007, Carter & Baker 17729 ( MMNS, VSC) . Peach Co.: Fort Valley , Jul 1915, [unknown collector] E3340 ( GA) . Taylor Co.: 6 mi W of Butler , 15 Jun 1952, Duncan & Hardin 13615 ( GA) .

Figures

FIG. 13.A,C.Chamaecrista deeringiana, Goulds,Miami-Dade Co.(photos by A.R. Franck).B. Chamaecrista horizontalis, isotype (NY);image courtesy of the C.V.Starr Virtual Herbarium of the New York Botanical Garden,http://sweetgum.nybg.org/science/vh/.D.Chamaecrista horizontalis, Davis 16081 (FLAS,sheet 2 of 2); image by Sophie Charles,courtesy of the University of Florida Herbarium (FLAS),Florida Museum of Natural History.

FIG. 14.Distribution of Chamaecrista deeringiana (triangles) and C.horizontalis (dots).Occurrences of C.horizontalis in Bay Co.and Holmes Co.,Florida, and Sumter Co., Georgia,are based on specimens that were cited in Pullen (1963), and the occurrence in Mississippi is based on Sorrie and Leonard (1999).