Actinocladum verticillatum McClure ex Soderstrom (1981: 1204
Creators: name: Lopes-Neto, Raimundo Balieiro
name: Viana, Pedro Lage
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Poales
Poaceae
Actinocladum
Actinocladum verticillatum

description: 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.
description: Published as part of 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, pp. 99-129 in Phytotaxa 550 (2) on pages 102-104, DOI: 10.11646/phytotaxa.550.2.2, http://zenodo.org/record/6641088