Festuca dissitiflora, Steudel ex Grisebach, 1879

Ospina, Juan C., 2016, New lectotypifications and new synonyms in Festuca (Poaceae, Pooideae, Loliinae) from the Central Andes, Phytotaxa 247 (4), pp. 247-258 : 249-251

Festuca dissitiflora and related taxa

Morphology —All diagnostic vegetative and reproductive morphoanatomical characters cited for Festuca dissitiflora , F. castilloniana , and F. potosiana overlap; these taxa form a morphological continuum. However, these species differ from F. circinata by the following vegetative and reproductive characters: scabrous leaf sheaths (vs. glabrous), obtuse lobes of the auricles (vs. truncate), erect leaves with scabrous abaxial surfaces (vs. circinate, glabrous), obtuse blade apices (vs. acute), linear-acute glumes (vs. ovate-lanceolate), and apices of the lemma acute bidentate (vs. entire). These species differ from F. loricata , F. villipalea , and F. erecta var. aristulata (including F. fiebrigii ) by their floriferous culms without nodes or rarely 2 nodes (vs. more than 4–5 nodes), permanently closed and conduplicates leaves (vs. expanded flat leaves occasionally rolled in when dry), acute blade apices (vs. obtuse), ovate-lanceolates glumes (vs. linear-acute), and apices of the lemmas entire (vs. acute-bidentate).

Leaf-blade anatomy —The outlines of leaf cross sections of Festuca dissitiflora , F. castilloniana , and F. potosiana are rounded, with distinguishable adaxial and abaxial ribs, ribs associated with 3–4 vascular bundles of first and second orders between the midrib and the margin, all situated on the abaxial surface. The sclerenchyma is arranged in small and well-developed subepidermal strands, which are not in contact with the vascular bundles, and formed by 2–3 cells on the adaxial side only. Bundle sheaths are round, complete or occasionally with small interruptions only on the abaxial surface, not extended, and formed by 13–16 relatively small cells ( Fig. 1a–c ).

In Festuca circinata the outline of the leaf cross section is elliptical, with adaxial ribs distinguishable and no abaxial ribs developed (smooth), ribs associated with 5–6 vascular bundles between the midrib and the margin of first and second orders all situated close to the abaxial surface. The sclerenchyma is arranged in a continuous ring formed by 2–3 cells on the abaxial side of the leaf section, and with well-developed T-shaped girder sclerenchyma cells with relatively long stems in contact with vascular bundles on the adaxial side. Bundle sheaths are round, incomplete with abaxial and adaxial interruptions and not extended, formed by 4–5 small cells ( Fig. 1d ).

The outlines of the leaf cross sections in Festuca fiebrigii , F. erecta var. aristulata , F. loricata , and F. villipalea have expanded and undulating outlines, with undulating abaxial surfaces and ribs distinguishable on the adaxial surfaces, ribs associated with (8–)9–10 vascular bundles between the midrib and the margin of first order and third orders all situated in different levels of the blade. The sclerenchyma is arranged in well-developed girders that narrower towards the bundle, triangular or trapezoidal, formed by 5–6 cells at the abaxial and adaxial side of the leaf section, with relatively long stems in contact with vascular bundles on adaxial side. Bundle sheaths are round, incomplete with abaxial and adaxial interruptions and extended, formed by 8–13 small cells ( Fig. 1e ).

Leaf-blade epidermal micromorphology —The abaxial leaf surfaces of Festuca dissitiflora ( Figs. 2a–b ), F. castilloniana ( Figs. 2c–d ), and F. potosiana ( Figs. 2 e–f ) are heterogeneous, with differences between costal and intercostals areas; sparse epicuticular wax in threads subtype; rectangular cells that are usually more than eight times longer than wide; isodiametric short cells with silica bodies; prickles found along the costal zone in one row, which are sparse; and stoma and macro-hairs are absent. The adaxial surfaces are homogeneous, with differences between costal and intercostals areas. They have the same subtype of epicuticular wax; long and short cells are similar; stoma are present in the intercostal zones, forming rows parallel to the long cells, with a homogeneous distribution and frequency; macro-hairs are absent; and prickles are present in costal and intercostal zones, with variable apex orientations.

Festuca fiebrigii , F. erecta var. aristulata , F. loricata , and F. villipalea are homogeneous abaxial leaf surfaces, the intercostal and costal areas are slightly different, the epicuticular wax is absent; rectangular long cells are usually more than six or seven times longer than wide, the short cells with silica bodies are isodiametrics; the prickles are present on the costal and intercostals zone, and they are scattered; stoma and macro-hairs are absent ( Fig. 2g ). The adaxial surfaces are homogeneous, the intercostal and costal areas are differentiated, the epicuticular wax is sparse in platelets subtype; the long cells more than five times shorter than wide, the short cells are absent; the stoma are situated on intercostal zones (forming rows parallel to the long cells), with homogeneous distribution and frequency; macro-hairs are present at the costal and intercostals zones, with the orientation in different directions, sparse; prickles are absent or rare at the margin of the blade ( Fig. 2h ).

The abaxial leaf surface in Festuca circinata ( Figs. 2i–j ) is homogeneous, the intercostal and costal areas are not differentiated, the epicuticular wax absent; the long cells are rectangular and more than seven times shorter than wide, the short cells with silica bodies are isodiametric; stoma, macro-hairs, and prickles are absent. The adaxial surface is homogeneous, the intercostal and costal areas are differentiated, epicuticular wax is the same to abaxial surface; the long and short cells showed similar micromorphology; the stoma are situated on intercostal zones, with heterogeneous distribution and frequency; macro-hairs are absent; the prickles are usually orientated toward the apex, abundant, with homogeneous distribution on adaxial surface.

Figures

FIGURE 1. Leaf-blade cross section. a. Festuca dissitiflora (Barros A. 39, BAA). b. Festuca castilloniana (Castillón L. 2884, LIL). c. Festuca potosiana (Renvoize S. A. et al. 5294, LPB). d. Festuca circinata (Hieronymus G. H. E. W. 535, CORD). e. Festuca fiebrigii (Fiebrig K. A. G. 3118, BAA). Scale bars a, c = 100μm, b, d, e = 200 μm.

FIGURE 2. Micromorphology of abaxial and adaxial leaf blade epidermis. a–b. Festuca dissitiflora (Barros A. 39, BAA). c–d. Festuca castilloniana (Castillón L. 2884, LIL). e–f. Festuca potosiana (Renvoize S. A. et al. 5294, LPB). g–h. Festuca fiebrigii (Fiebrig K. A. G. 3118, BAA). i–j Festuca circinata (Hunziker A.T. 9042, BAA). Scale bars a = 100 μm, b = 50 μm, c = 200 μm, d = 100 μm, e = 200 μm, f = 200 μm, g = 50 μm, h = 50 μm, i = 200 μm, j = 100 μm.