Trichostema microphyllum K. S. McClell., 2023

Mcclelland, R. Kevan Schoonover, Weakley, Alan S. & Poindexter, Derick B., 2023, Seven new species of Trichostema (Lamiaceae: Ajugoideae) from the North American Coastal Plain biodiversity hotspot, Phytotaxa 603 (2), pp. 95-149 : 126-129

Trichostema microphyllum K. S. McClell. sp. nov. ( Figures 22 and 23 )

Diagnosis: —Virgate perennial to 60 cm tall, morphologically most similar to Trichostema suffrutescens . It differs from T. suffrutescens by its narrower leaves of 0.28–0.42 cm (vs. 1.13–1.74 cm), presence of spreading trichomes on the stem and at nodes (vs. downwardly curved), and a geographic restriction to the Brooksville Ridge and sandhill and scrub habitats to the west (vs. a geographic restriction to the Trail, Mt. Dora, Orlando, and northern Lake Wales Ridges).

Type: — U.S.A. Florida. Citrus County. Sandy, xeric open forest, Withlacoochee State Forest , Citrus Tract along first trail crossing over Trail 11 B south of its intersection with Trail 20, 7 October 2018, R. Kevan Schoonover McClelland 190a–d (holotype NCU!; isotypes FLAS!, NY!, USF!). Note: Specimens R. Kevan Schoonover McClelland 190a–d represent a single gathering in accordance with Article 8.2 of the ICN ( Turland et al. 2018) .

Suffrutescent perennial to 60 cm tall; branching primarily in the lower to middle part of the plant; stem hairs spreading, occasionally upwardly curved, rarely downwardly curved to three cells long ( Figure 1j ), with sessile glands; node hairs spreading to upwardly curved, to three cells long ( Figure 1j ); leaves widest towards the tip, 1.1–1.49(–1.9) × (0.24–)0.28–0.42(–0.54), average of 1.28 × 0.35, cm, (3–)3.2–4.31(–5.42), average of 3.76, times long as wide, base cuneate to attenuate, margin entire, apex rounded, rarely obtuse to acute or emarginate; inflorescence hairs spreading to upwardly curved, to three, rarely to four, cells long, with sessile and spreading glands to two cells long (including gland); bracts widest towards the tip, (2.8–)3.58–5.18(–6.4) × (0.5–)0.9–1.61(–1.9), average of 4.38 × 1.25, mm, (2.56–)2.7–4.77(–5.82), average of 3.73, times long as wide, base cuneate to attenuate, margin entire, apex rounded, rarely obtuse to acute or emarginate; fruiting calyx (5–)5.19–5.94(–6.3), average of 5.56, mm long; buds purple-black to dark blue-purple, corolla dark blue or blue-purple to blue or blue-purple; anthers dark blue or blue-purple to blue or blue-purple; style bifid, the longer arm 3.5–4.5 times as long as the shorter; mature nutlets alveolate, (1.4–)1.47–1.75(–1.8), average of 1.61, mm long, hilum (0.4–)0.47–0.62(–0.7), average of 0.55, mm long, (0.25–)0.29–0.39(–0.43), average of 0.34, times the length of the nutlet alveoli small, rarely mid-sized, ridges tall, rarely mid-sized ( Figure 2k ).

Phenology: —Flowers and fruits September to November.

Etymology: —The epithet microphyllum (micro: Latin, small; phyll: Latin, leaf) is given to this species since it has the smallest leaves by leaf area of any Trichostema . The common name Small-leaved Bluecurls is given to this species for the same reason.

Habitat and distribution: — Trichostema microphyllum occurs in sandhills and sandhill-scrub ecotones; 10—100 meters; USA: Florida: Alachua, Citrus, Hernando, Levy, Marion, and Pasco Counties. ( Figure 24 )

Conservation status: —This species is restricted to the Brooksville Ridge and xeric habitats to the west. While the full extent of its range is possible to predict, how common it is in this range has been difficult to determine. The Citrus and Croom tracts of Withlacoochee State Forest represent the largest and highest quality habitats for this species and most observations of this species have been from these two properties. Based on the data collected for this study, this species should be recognized at a G2 ranking (NatureServe 2020).

Additional specimens examined (paratypes): — U.S.A. Florida, Alachua County: just W of Archer, 15.8 mi W of Gainesville on hwy US- 24., 25 October 1969, Faircloth 6406 ( NCU!); 4 mi. NW of Archer on SR 24 ., 7 December 1985, Flietner 39 ( WILLI!); west of Archer, 25 November 1921, Small, Small & DeWinkeler 10046 ( DUKE!, FLAS!, US!); Hernando County: Plants of the Weeki Wachee Area , SR 595 , 27 September 1971, Genelle & Fleming 1005 ( USF!); Withlacoochee State Forest: Croom Tract , 28.586561 N, 82.255447 W, 16 October 2021, McClelland & Schoonover 217 ( NCU!); About 2 miles e. of Weekiwachee springs., 16 October 1959, Ray, Jr. 9533 ( USF!); 0.7 mi W of US 19 on FLA 595, T23 S, R17 E, Sect. 30., 28.455521 N, 82.641607 W, 16 October 1982, Wunderlin & Beckner 9441 ( USF!); Levy County: Archer Sandhills, State Road 24, 1 mile from Alachua County border by microwave tower., 29 October 1989, Amoroso & Amaroso 153 ( GA!); Levy County , 2 October 1948, Ford 2344 ( FLAS!); Goethe State Forest - Bailey Mine , 29.458953 N, 82.550275 W, 4 November 2018, McClelland 204 ( NCU!); Goethe State Forest : Bailey Mine Tract , 29.454238 N, 82.548642 W, 16 October 2021, McClelland & Schoonover 221 ( NCU!) .

Figures

FIGURE 1. Detail of the stem and node trichomes of Trichostema section Trichostema. A) Trichostema dichotomum, B) T. setaceum, C) T. suffrutescens, D) T. nesophilum, E) T. floridanum, F) T. fruticosum, G) T. bridgesii-orzellii, H) T. gracile, I) T. hobe, J) T. microphyllum. Photos by R. Kevan Schoonover McClelland.

FIGURE 2. Detail of the nutlets of Trichostema section Trichostema. A) Trichostema dichotomum, B) T. setaceum, C) T. suffrutescens, D) T. nesophilum, E) T. floridanum, F) T. fruticosum, G) T. latens, H) T. bridgesii-orzellii, I) T. gracile, J) T. hobe, K) T. microphyllum. Trichostema dichotomum (A) shows large alveoli and tall ridges. T. latens (G) shows small alveoli and shorter ridges. Photos by Derick Poindexter.

FIGURE 22. Holotype specimen of Trichostema microphyllum in situ. Photo by R. Kevan Schoonover McClelland.

FIGURE 23. Holotype specimen of Trichostema microphyllum. Photo by R. Kevan Schoonover McClelland.

FIGURE 24. Approximate range of Trichostema microphyllum based on field data and herbarium records.