Podagrostis liebmannii (E. Fourn.) Sylvester & Soreng, 2020

Sylvester, Steven P., Peterson, Paul M., Romaschenko, Konstantin, Bravo-Pedraza, William J., Cuta-Alarcon, Lia E. & Soreng, Robert J., 2020, New combinations and updated descriptions in Podagrostis (Agrostidinae, Poaceae) from the Neotropics and Mexico, PhytoKeys 148, pp. 21-50 : 21

Podagrostis liebmannii (E. Fourn.) Sylvester & Soreng comb. nov. Fig. 3

Agrostis liebmannii (E. Fourn.) Hitchc., N. Amer. Fl. 17(7): 519. 1937. Apera liebmannii E. Fourn., Mexic. Pl. 2: 97. 1886.

Type.

Mexico. [Veracruz:] Orizaba, M. Botteri 93 in part (lectotype, designated here: P (P00740547 [image!]); isolectotypes: MSC fragm. ex P; epitype, designated here: Mexico. [Puebla:] Chinantla, May 1841, F.M. Liebmann s.n. " Plantae mexicanae Liebmann #12591" {handwritten on label} (US (US00595641!)). Syntype: Mexico. [Puebla:] Museum Botanicum Hauniense | Plantae mexicanae Liebmann | 1841-43 {printed label}, Gramineae N. 710 | Apera liebmannii Fourn. | [determ.] Fournier | Chinantla. May 1841, {handwritten on label} (NY (NY00345814 [image!]), US [not seen]).

Description.

Tufted perennial forming lax tufts, with the basal foliage reaching c. 11 cm tall and inflorescences well-exserted from the basal foliage. Tillers extravaginal. Culms 35-80 cm tall, erect, simple, delicate; nodes and internodes terete, nodes smooth, internodes and segment below the panicle smooth throughout (or smooth proximally and lightly scaberulous towards their apices in Moore 3339), usually with at least 1 or 2 elongated internodes visible, with 1-2 nodes exposed at flowering, uppermost internode c. 5.5-11.2 cm long, longer than the sheath. Leaves basal and cauline; sheaths terete, glabrous, lower sheaths tending to be smooth, upper sheaths lightly to densely scabrous with short hooks; flag sheath 8-11.5 cm long; basal sheaths 0.5-1 cm long, striate, becoming fibrous, smooth; ligules c. 0.5-4 mm long, membranaceous or scareous, usually strongly decurrent with the sheath, abaxially scabrous; upper culm ligules 1.5-4 mm long, obtuse to acute, sometimes slightly erose towards the apex; ligules of tillers shorter to those of the culm, c. 0.5-1 mm long, truncate to acute; blades 2-8.6 cm long, (0.5-)1-3.5 mm wide in diameter, flat, flaccid to firm, basal blades sometimes very narrow, abaxial surfaces glabrous, smooth to lightly scabrous, or usually more densely scabrous further up the culm, adaxial surfaces glabrous, smooth to lightly scabrous on the veins, scaberulous further up the culm, edges scaberulous. Panicles 7-18 × (1-)2.5-7 cm, open to slightly congested following anthesis, usually ovoid; panicle branches ascendant to patent, branched above the middle, filiform, with spikelets not present near the base, smooth, longest branches 2-4.7 cm long; pedicels 1.5-5 mm long, usually longer than the length of the spikelets, divaricate, smooth or lightly scaberulous. Spikelets (1.8-)2-2.1 mm long; glumes remaining on the inflorescence at maturity, equal or subequal, the lower usually slightly longer than the upper, subequaling the length of the floret to 0.4 mm longer, lanceolate, slightly keeled, apices acute, glabrous, keels lightly scaberulous just in the distal 1/3, surfaces smooth; lower glume 1- (or 3-)veined, lateral veins, if present, vestigial; upper glume 1- (or 3-)veined, lateral veins, if present, vestigial; lemmas 1.7-2 mm long, glabrous, smooth, strongly 5-veined with excurrent prominent veins, apex broadly acute, awn absent; paleas well-developed, 1.4-1.9 mm long, usually reaching from ¾ to subequaling the lemma, keels obscure, smooth, apex bifid and sometimes erose; rachilla prolonged from the base of the floret, 0.3-0.5 mm long, glabrous, smooth. Calluses not or slightly elongated, 0.05-0.1 mm long, glabrous, smooth. Flowers; lodicules c.0.3-0.4 mm long, lanceolate with acuminate apices, not lobed; anthers 3 in number, 0.6-1 mm long. Caryopses not seen. 2 n = unknown.

Distribution and ecology.

Mexico, endemic. The authors have only verified specimens from Hidalgo, Puebla and Veracruz states of central Mexico, with Beetle (1983), Dávila et al. (2018), and Sánchez-Ken (2019) mentioning the species to range from Durango state in the north to Oaxaca state in southern Mexico. Found in humid areas of pine and fir forests, Sphagnum bogs, and by streams, 2100-2300 m ( Beetle 1983).

Other specimens examined.

Mexico. Hidalgo: Distrito Zacualtipan, pine woods and Sphagnum bogs about 3 miles from Zacualtipan on road to Tianguistengo, 2100 m alt., 4 July 1947, H.E. Moore, Jr. 3339 (US00486609).

Notes.

Beetle (1983) appears to consider Agrostis durangensis Mez a synonym of A. liebmannii , and states A. liebmannii to be distributed as far north as Durango state based on the type locality of A. durangensis . However, we consider A. durangensis to be a synonym of A. exarata Trin. and have only verified specimens from as far north as Hidalgo state. Herrera-Arrieta (2001) cite A. liebmannii for Durango state based on specimen Palmer 190 (US00486604), which is treated here as A. exarata . Herrera-Arrieta (2014), Dávila et al. (2018) and Sánchez-Ken (2019) also mention Agrostis liebmannii to be found as far north as Durango state, but do not include voucher specimens and may have based this on Beetle’s (1983) and Herrera-Arrieta’s (2001) treatments. Certain characteristics in Beetle’s (1983: 82) description of A. liebmannii also do not fit the specimens examined, which may be due to the author’s inclusion of A. durangensis in the species circumscription. Spikelet size of 2.5 mm mentioned by Beetle (1983: 82) does not fit the specimens studied which had spikelets (1.8-)2-2.1 mm long, although Beetle’s (1983: 73) key to species separates A. liebmannii from A. hiemalis var. laxiflora (Michx.) Beetle (= Agrostis scabra Willd.) based on spikelets being c. 2 mm long and shorter than 2.5 mm long. Beetle’s (1983) mention that the tiller blades are more-or-less involute was also not seen, although specimen Moore 3339 (US00486609) was intermixed with another species with involute blades, which might explain this.

Podagrostis liebmannii bears close affinity to P. thurberiana , a North American species that is found as far south as California ( Hitchcock et al. 1969; Harvey 2007). These similarities include a) the overall habit, with tall culms, loosely tufted and subrhizomatous habit with extravaginal shoots; b) spikelet morphology, with spikelets usually <2.3 mm long, lemmas with excurrent prominent veins and paleas almost subequalling the lemma; c) panicles open and becoming slightly congested following anthesis; d) flat leaf blades. Podagrostis liebmannii can be distinguished from the aforementioned species by a) panicles generally much larger, 8-18 × (1-)2.5-7 cm, with patent panicle branches at anthesis (vs. 5-14 × 0.2-3 cm, panicle branches usually ascending at anthesis in P. thurberiana ); b) callus glabrous (vs. with short hairs to 0.5 mm long emerging from the basal side-ridges of the callus in P. thurberiana ); c) rachilla glabrous, smooth (vs. short hairs to 0.3 mm long emerging from the apex of the rachilla in P. thurberiana ).

Fournier (1886: 97) cited two specimens, Liebmann 710 and Botteri 93, in the protologue but only indicated the P herbarium for the Botteri 93 specimen. As we are sure that Fournier saw the Botteri 93 specimen at P, we lectotypify on this collection. Because both the Botteri 93 and Liebmann 710 material included just an inflorescence culm and part of the flag leaf and did not show the basal parts of the plant, we also epitypify the lectotype on Liebmann s.n. (US00595641) that was collected on the same date and at the same locality as the Liebmann 710 collection and includes the basal portion of the plant to help interpret the lectotype. The epitype Liebmann s.n. (US00595641) cited here may in fact be a duplicate of the Liebmann 710 syntype that Fournier (if he ever saw it) did not annotate at the Copenhagen herbarium. The US specimen identified as Agrostis liebmannii (" Apera " not mentioned) was catalogued as Plantae mexicanae Liebmann #12591; these catalogue numbers are often followed by Liebmann’s field numbers such as the handwritten “710”. The Copenhagen herbarium does not have a Liebmann duplicate bearing either of these numbers, or either of the synonyms.

Figures

Figure 3. Podagrostis liebmannii. A Whole plant B ligular area of flag leaf C section of inflorescence showing spikelets D floret, ventral view, with the rachilla prolongation indicated with a red arrow. Images of epitype specimen Liebmann s. n. (US 00595641) courtesy of the United States National Herbarium (US).