Actinocladum verticillatum (Nees 1829: 523) McClure ex Soderstrom (1981: 1204)

Lopes-Neto, Raimundo Balieiro & Viana, Pedro Lage, 2022, Flora of the Serra do Cachimbo (Eastern Amazon, Brazil): Bambusoideae (Poaceae), including the description of two new species, Phytotaxa 550 (2), pp. 99-129 : 102-104

Actinocladum verticillatum (Nees 1829: 523) McClure ex Soderstrom (1981: 1204)

≡ Arundinaria verticillata Nees (1829: 523) . Fig. 2 A–C .

Type :— BRAZIL (as “Brasilia”, no further locality given). Collector expeditions between 1814 and 1829, Sellow s.n. (holotype B, isotypes K-000433176, LE-TRIN-3173.01, US-2808995 , US-557548 ) .

Rhizomes not seen.Culms 2–5 m tall, ca. 2.5 cm in diameter, erect, internodes 25–38 cm, pithy, smooth, stramineous; primary buds subequal, prophyll unitary, 5.1–5.9 × 1.3 mm, glabrous except at the apex shortly pilose, margins ciliate at the apex; nodes dark brown, glabrous, horizontal, supranodal ridge inconspicuous. Branch complement with 12–17 subequal, widely spreading branches, ca. 26 cm long, ca. 1 mm in diameter, internodes 8–14 cm long. Midculm culm leaves caducous, but the blade falling first, stramineous at maturity; sheaths 7.5–7.8 × 3.4–3.6 cm, shorter than the blade, glabrous on both surfaces, margins densely ciliate, with stramineous trichomes; auricles inconspicuous; fimbriae “ruffle-like” at the sheath summit, erect, stramineous; inner ligule ca. 2 mm long, ciliate; blades 4 × 0.7–0.9 cm, heart-shaped, abaxially shortly pubescent, with dark trichomes on the nerves, adaxially densely ciliate, with hyaline trichomes, margins shortly ciliate, with hyaline trichomes, apex acuminate; terminal culm leaf sheath persistent and blade caducous; sheaths 3.2–4.5 × 4 cm, stramineous (in siccus), puberulent, margins ciliate; auricles inconspicuous; fimbriae ca. 4 mm long; 8–10 overlapping leaves, 16–16.5 × 2–2.5 cm, broad lanceolate, convex, often reflexed, glabrous, margins scabridulous, apex acuminate. Foliage leaves 6–8 per complement; sheath 3–4 × 4 cm, stramineous (in siccus), glabrous on both surfaces, margins densely ciliate; auricles present, ca. 4 mm long; fimbriae 4.2–5.1 mm, erect, stramineous (in siccus); inner ligules ca. 0.3 mm long, symmetrical, membranous; outer ligule ca. 0.2 mm long, symmetrical, membranous-ciliate; pseudopetioles ca. 3.7 mm, flat, glabrous; blades ca. 9.2 × 12.3 cm, linear-lanceolate, glabrous on both surfaces, 38–49-nerved, midnerve slightly excentric, base rounded, margins shortly ciliate, apex acuminate. Synflorescences 14.2–15 cm long; pedicels 8–9 cm long, puberulent; subtending bracts ca. 4 × 2 mm, caducous, elliptic, glabrous, margins ciliate, apex acuminate. Spikelets 38–40 × 3–4 mm, linear-lanceolate, comprising 2 glumes, 7–10 fertile anthecia; lower glume 10–12 × 3 mm, ovate-triangular, 5-nerved, stramineous (in siccus), glabrous, margins glabrous, apex apiculate; upper glume ca. 9–10 × 2.8–3.2 mm, ovate-triangular, 10-nerved, stramineous (in siccus), glabrous, margins glabrous, apex apiculate; rachilla segments short-pilose. Fertile anthecium 13–15 × 2–3 mm, ovate-lanceolate; lemma 13-nerved, glabrous and scabridulous toward the apex, margins glabrous, overlapping and covering the rachilla segments, apex acuminate; palea 2-keeled, concave between the keels where the rachilla segment fits, 2 broad wings around the floret, 6-nerved between the keels and 5-nerved in each wing, slightly exceeding the lemma, glabrous except the short-ciliate keels, margins glabrous, apex acuminate; lodicules 3, one shorter than the others, deltoid, glabrous, apex pointed; stamens 3, filaments ca. 2 mm long, glabrous, anthers ca. 8 mm long, yellowish (in siccus); ovary ca. 2 mm long, fusiform, glabrous, upper portion expanded and short-pubescent, style ca. 2 mm long, pubescent, stigma 2. Caryopsis not seen.

Specimens examined: — BRAZIL. Mato Grosso: Guarantã do Norte, Estrada Guarantã do Norte-Cachimbo, ca. 13 km antes da divisa com o estado do Pará , 26 April 1997, Souza et al. 15810 ( ESA, HUEFS). Pará : Altamira , Reserva Biológica Nascentes da Serra do Cachimbo , Cachoeira do Curuá , 337 m, 8°44’01.3”S, 54°57’44.1”W, 30 September 2019, Maciel-Silva et al. 507 ( MG) .

Additional specimens examined: — BRAZIL. Distrito Federal : Brasília , Barragem do lago Paranoá, encostas do morro adjacente à barragem, 16 October 1984, Filgueiras 1151 ( MG) .

Distribution and habitat: —This species is found in Bolivia and Brazil ( Soderstrom 1981, Judziewicz et al. 2000). It is characteristic of the Brazilian Cerrado and occurs in the North (AM and PA), Northeast (BA), Central-West (DF, MT and MS) and Southeast (MG and SP) regions (Andrade et al. 2020). In the Serra do Cachimbo, this species was found in Open ombrophilous forest.

Comments: — Actinocladum verticillatum is a woody bamboo with erect culms, ca. 5 m tall, and it can be recognized by the aspidate branch complement and the dimorphic culm leaves; midculm leaf sheaths with fimbriae “ruffle-like” at the apex, the blades heart-shaped; and the terminal culm leaf complement with 8–10 overlapping leaves, the blades broad lanceolate. The synflorescence is composed of long-pedicelled spikelets, the pedicels 8–9 cm long, the spikelets ca. 38 × 3 mm, linear-lanceolate. In the Serra do Cachimbo, Merostachys cachimboensis Lopes-Neto & P.L.Viana also possesses an aspidate branch complement, but it differs in its clambering habit and homomorphic culm leaves, bearing free fimbriae and linear-lanceolate blades.

Figures

FIGURE 2. Field photographs of bamboos from Serra do Cachimbo. A–C. Actinocladum verticillatum: A–B. Habit. C. Culm leaves. D–I. Arthrostylidium simpliciusculum: D. Habit. E. Branch complement. F. Culm leaf sheath margins. G. Culm leaf apex. H. Foliage leaf complement. I. Foliage leaf fimbriae. J–N. Eremocaulon capitatum: J. Habit. K. Infra- and supranodal bands of trichomes and culm leaves. L. Foliage leaf fimbriae. M. Synflorescence. N. Pseudospikelets. O–R. Guadua paniculata: O. Habit. P. Infra- and supranodal bands of trichomes and thorns. Q. Foliage leaf complement. R. Culm leaves. Photos: P.L.Viana (A–K, M–O, R) and M.Pastore (L, P).