Raddiella esenbeckii C. E. Calderon & Soderstrom 1980
Creators: name: Lopes-Neto, Raimundo Balieiro
name: Viana, Pedro Lage
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Poales
Poaceae
Raddiella
Raddiella esenbeckii

description: Raddiella esenbeckii (Steudel 1855: 90) C.E. Calderón & Soderstrom (1980: 21)
≡ Panicum esenbeckii Steudel (1855: 90). Fig. 7 H–I.
Lectotype (designated by Zuloaga & Judziewicz 1991):— BRAZIL. Amazonas: Rio Negro, Ega, Martius s.n. [lectotype M, isolectotype US-2877939 (fragment ex M)].
Rhizomes absent. Culms 8–40 cm tall, sprawling, decumbent to geniculate, the erect portions wiry, internodes 2.5–3.2 cm, pithy in center, smooth, glabrous to sparsely pilose with short, retrorse trichomes; nodes thickened, densely pilose with whitish retrorse trichomes. Leaf sheaths glabrous to short-pilose, densely toward the summit; ligules ca. 0.3 mm, membranous-ciliate; pseudopetioles 0.5–0.8 mm, densely pilose; blades 1.5–1.8 × 0.5–0.6 cm, ovate-triangular, firmly membranous, densely puberulent on both surfaces or glabrous on the abaxial surface and short-pilose near the base of the adaxial surface, asymmetrical, base truncate, ciliate in the lower margins, apex acute or short-apiculate. Terminal synflorescences 4–5 mm long, with male spikelets only, rachis short-pilose, pedicels ca. 2.5–5 mm long, filiform, minutely cupuliform at the apex, short-pilose. Axillary synflorescences ca. 1.3 cm long, with both male and female spikelets, male spikelets (1–)2–4, female spikelets 2, partially included in the leaf sheath, rachis shortpilose, pedicels 1–2 mm long, filiform, short-pilose. Male spikelets ca. 3 mm long, lanceolate, hyaline (in siccus), glabrous to sparsely hispid with short trichomes, falling entire; glume occasionally present, ca. 2 mm long, linearlanceolate, 1-nerved, membranous, shortly hispid, apex acuminate; lemma 3-nerved, glabrous to sparsely hispid with short trichomes, apex acuminate; palea 2-nerved, glabrous to sparsely hispid with short trichomes, apex acuminate; stamens 2, included, filaments 0.05 mm long, glabrous, anthers ca. 1.3 mm long, black (in siccus). Female spikelets ca. 2.1 × 1 mm, ovoid, greenish (in siccus), sparsely to densely short-pilose, membranous, the internodes between the glumes thickened, glumes deciduous; lower glume ca. 2.1 × 1 mm, 3-nerved, apex acuminate; upper glume ca. 2 × 1 mm, 3-nerved, apex acute; anthecium ca. 1.3 × 1 mm, ellipsoid, whitish (in siccus), compressed, coriaceous, deciduous; lemma 3-nerved, glabrous, apex acute; palea 2-nerved, glabrous, apex acute; ovary ca. 0.2 mm, ellipsoid, glabrous, style ca. 1 mm, glabrous to sparsely short-pilose, stigma 2, plumose. Caryopsis not seen.
Specimens examined: — BRAZIL. Mato Grosso: Colider, Estrada Santarém-Cuiabá, BR 163 km 762, a 30 km de Guarantã, 19 April 1983, Amaral 806 (MG, INPA, MO, RB, US). Guarantã do Norte: Estrada Guarantã do Norte-Cachimbo, ca. 8 Km antes da divisa com o Estado do Pará, 26 April 1997, Souza et al. 15861 (ESA); ca. 13 Km antes da divisa com o Estado do Pará, 26 April 1997, Souza et al. 15805 (ESA); ca. 18 Km antes da divisa com o Estado do Pará, 26 April 1997, Souza et al. 15767 (ESA, UFMT). Pará: Altamira, Cachoeira do Rio Curuá, BR- 163 a 600 km de Itaituba-PA, 24 May 2005, Silva 1441 (HUEFS); ibidem, 8°44’01.2”S, 54°57’45.5”W, 28 May 2021, Lopes-Neto et al. 767 (MG).
Distribution and habitat: —This species is found in Central and South America, from Panama to Bolivia and Central Brazil (Zuloaga & Judziewicz 1991). In Brazil, it is registered in the North (AM, AP, PA, RO, RR and TO), Northeast (BA, MA and PI), Central-West (DF, GO, MT and MS), Southeast (MG and SP) and South (PR) regions (Oliveira & Oliveira 2020). It can be found in gallery forests and savannas, in semi-shaded or dryish open areas, up to 1.500 meters (Zuloaga & Judziewicz 1991). In the Serra do Cachimbo, it was found in Campo cerrado, Campo rupestre and Open ombrophilous forest.
Comments: — Raddiella esenbeckii and R. minima Judziewicz & Zuloaga (in Zuloaga & Judziewicz 1991: 939) share asymmetrical ovate-triangular leaves, that are truncate at the base and female spikelets with persistent glumes. However, R. esenbeckii is easily recognized by the culms 8–40 cm tall (vs. 3–6 cm long in R. minima), blades 1.5–1.8 cm long (vs. 0.4–0.6 cm long) and the axillary synflorescences bearing male and female spikelets (vs. the axillary synflorescences bearing only female spikelets). It also can be distinguished by the long-ellipsoid caryopsis, with the hilum short-linear, ca. 1/3 the length the caryopsis (Zuloaga & Judziewicz 1991).
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 page 123, DOI: 10.11646/phytotaxa.550.2.2, http://zenodo.org/record/6641088