Agrostis elliottiana Schult., Mant. 2: 202. 1824.

Vigosa-Mercado, J. Luis, Delgado-Salinas, Alfonso, Alvarado Cardenas, Leonardo O. & Eguiarte, Luis E., 2023, Revision of the genus Agrostis (Poaceae, Pooideae, Poeae) in Megamexico, PhytoKeys 230, pp. 157-256 : 157

4. Agrostis elliottiana Schult., Mant. 2: 202. 1824.

Figs 4D , 5D , 13

Agrostis arachnoides Elliott, Sketch Bot. S. Carolina 1(2): 134. 1816, nom. illeg. hom., non Poir., 1810. Type: USA. South Carolina near Orangeburgh, I.S. Bennet s.n. (holotype: CHARL (CHARL-BY3758 [image!])).

Notonema arachnoides Raf., Neogenyton 4. 1825.

= Agrostis exigua Thurb., Bot. California 2: 275. 1880. Type: USA. California: foothills of the Sierras, H.N. Bolander s. n. (holotype: GH (GH00022956 [image!]); isotypes: MO (MO-123096 [image!]), US (US00156423[image!])).

Notonema arachnoides Raf. ex B.D. Jacks., Index Kew. 2: 319. 1894, nom. inval., pro syn.

= Agrostis elliottiana Schult. fo. molesta Shinners, Rhodora 56(662): 28. 1954. Type: USA. Texas: Wood County, sandy upland pine woods 2.7 miles east of Mineaola, 23 Apr 1953, L.H. Shinners 14372 (holotype: BRIT (BRIT408703 [image!])).

Type.

Based on Agrostis arachnoides Elliott.

Description.

Plants annual, caespitose. Tillers absent. Culms 5-45 cm long, erect, sometimes geniculate at the base, nodes (3-)4-9, glabrous, internodes glabrous. Leaves basal and cauline; sheaths 1-5 cm long, longer or shorter than the internodes, glabrous or scaberulous; ligules (0.7-)1.5-3.5(-5) mm long, longer than wide, dorsally scaberulous, apices rounded to truncate, lacerate; blades 0.5-4(-7) cm long, 0.5-1 mm wide, linear, flat, sometimes becoming conduplicated, scaberulous on both surfaces. Panicles (3-)5-20 cm long, (0.5-)2-12 cm wide, open, lax, linear to ovate, usually exserted from the upper sheaths, the whole panicle detaching after maturity; branches ascending to spreading, rebranching about or above mid-length, scaberulous, without spikelets near their base, inferior branches 2-8 cm long; pedicels 0.3-7.5 mm long, ascending to spreading, scaberulous. Spikelets 1.5-2.2 mm long, purplish; glumes equal to subequal, lanceolate, apices acute, 1-veined, scaberulous on the keel, sometimes margins distally scaberulous, lower glume 1.5-2.2 mm long, upper glume 1.3-2 mm long; callus pubescent, with 2 bunches of trichomes; lemmas 1-2 mm long, elliptic, apices entire, acute or toothed, 5-nerved, veins prominent, awned in the upper third, awn 3-10 mm, flexuous, deciduous; paleas absent, or up to 0.2 mm long, veinless, glabrous; anther 1, 0.1-0.2 mm long. Caryopsis 1-1.4 mm long, elliptic; endosperm liquid. 2n= 28 ( Harvey 2007).

Anatomy and micromorphology.

Leaf blades flat to v-shaped in transversal section; adaxial furrows deep, narrow; adaxial ribs triangular; keel absent; first order bundles circular in outline, sheath interrupted abaxially, abaxial and adaxial sclerenchyma in strands; second order bundles circular in outline, sheath interrupted abaxially, abaxial and adaxial sclerenchyma in strands; intercostal sclerenchyma present, abaxial; leaf margins with well-developed sclerenchyma caps, rounded; colorless cells absent (Fig. 6H, I ). Lemmas with transversal thickenings oblong, wider than the unthickened portions of the wall; prickle hairs abundant (Fig. 7D ).

Distribution and habitat.

Agrostis elliottiana is native to North America, distributed on the East Coast of USA, from Pennsylvania to Florida, and from northern California to Texas ( Harvey 2007). Herbarium specimens from the study zone of this species have been collected in southern Arizona and New Mexico, USA (Fig. 8D ). Agrostis elliottiana has also been reported from the Mexican state of Yucatán ( Beetle et al. 1983), but herbarium specimens associated with this record have not been found. This species grows in the edges of streams, in the middle of scrublands, with Arctostaphylos and Juniperus , between 1189-1676 m a.s.l. (Fig. 9G ). There are more records of this species in the study zone, on databases ( GBIF 2023a), but not all of them have images, and thus we were unable to confirm their identity.

Phenology.

Specimens with spikelets have been collected in April (Fig. 10G ).

Commentaries.

Agrostis elliottiana is often confused with A. hyemalis but differs from it in the annual habit of the plants, leaf blades sometimes conduplicated, with triangular adaxial ribs and abaxial intercostal sclerenchyma, spikelets not clustered, lemmas with a flexuous awn, and only one anther (vs. perennial plants, leaf blades flat, with rounded abaxial ribs, without intercostal sclerenchyma, spikelets clustered at branch tips, lemmas unawned, three anthers in A. hyemalis ).

Conservation status.

Agrostis elliottiana apparently is a rare species in the study zone. It is only represented by four collections, occurring in the Coronado National Forest. The EOO is 1,078 km2 and the AOO is 16 km2. Following the IUCN criteria, the preliminary assessment category is Endangered (EN).

Specimens examined.

USA. Arizona: Pima County, Arizona National Scenic Trail, Santa Catalina Mountains , Coronado National Forest , along 4WD road west of Bellota Ranch , 32.324417°N, 110.6547°W, 1189 m alt., 28 Apr 2005, W.C. Hodgson et al. 20220 (DES); Coronado National Forest , 6.8 mi E of Coronado National Forest boundary, along extension of Tanque Verde Road , [32.2516°N, 110.62°W], 1300 m alt., 28 Apr 1973, E. Lehto et al. 10924 (ASU [*, **]); E edge of Rincon Mountains , 4 km N of Pima-Cochise County line along USFS-35 (Mescal Road), [32.116667°N, 110.483333°W], 1330 m alt., 16 Apr 1986, J.R. Reeder 842 (MICH) . New Mexico: Hidalgo County, Peloncillo Mountains, Cloverdale Creek Canyon about 1.3 road mi NW of the Pendleton Ranch House , [31.448973°N, 108.986951°W], 1676 m alt., 20 Apr 1986, R.D. Worthington 14015 (COLO, DES, NY, UNM) .

Figures

Figure 4. Florets of Agrostis species observed with SEM A A. bourgaei B A. calderoniae C A. capillaris D A. elliottiana E A. exarata F A. ghiesbreghtii G A. gigantea H A. hyemalis I A. laxissima J A. microphylla K A. pallens L A. perennans M A. scabra N A. stolonifera O A. subpatens P A. subrepens Q A. tolucensis R A. turrialbae S A. variabilis. Scale bars: 0.3 mm.

Figure 5. Calluses of Agrostis species observed with SEM A A. bourgaei B A. calderoniae C A. capillaris D A. elliottiana E A. exarata F A. ghiesbreghtii G A. gigantea H A. hyemalis I A. laxissima J A. microphylla K A. pallens L A. perennans. Scale bars: 50 μm.

Figure 6. Leaf blade anatomy in transversal section of Agrostis species, in general view, and details of lateral bundles. A - C A. bourgaei D - E A. calderoniae F - G A. capillaris H - I A. elliottiana. Scale bars: 0.1 mm.

Figure 7. Lemma surface of Agrostis observed with SEM A A. bourgaei B A. calderoniae C A. capillaris D A. elliottiana E A. exarata F A. ghiesbreghtii G A. gigantea H A. hyemalis I A. laxissima J A. microphylla K A. pallens L A. perennans. Scale bars: 15 μm.

Figure 8. Map of known geographic distribution of Agrostis species, based on herbarium specimen data A A. bourgaei B A. calderoniae C A. capillaris D A. elliottiana E A. exarata F A. ghiesbreghtii.

Figure 9. Elevation histograms of Agrostis species A all records B native species C introduced species D A. bourgaei E A. calderoniae F A. capillaris G A. elliottiana H A. exarata I A. ghiesbreghtii J A. gigantea K A. hyemalis L A. idahoensis M A. laxissima N A. microphylla O A. pallens.

Figure 10. Phenology histograms of Agrostis species A all records B native species C introduced species D A. bourgaei E A. calderoniae F A. capillaris G A. elliottiana H A. exarata I A. ghiesbreghtii J A. gigantea K A. hyemalis L A. idahoensis M A. laxissima N A. microphylla O A. pallens.

Figure 13. Agrostis elliottiana A whole plant B ligular area C spikelet D floret, abaxial view F floret, adaxial view. Based on Lehto et al. 10924 (ASU). Scale bars: 3 cm (A); 5 mm (B); 0.5 mm (C); 0.3 mm (D, E).