Linum elongatum (Small) H.J.P.Winkler (1931: 116)

González-Velasco, Juan, Burgos-Hernández, Mireya, Galván-Escobedo, Iris G. & Castillo-Campos, Gonzalo, 2022, Taxonomic update of the flax family in Mexico, Phytotaxa 549 (2), pp. 141-184 : 152-154

Linum elongatum (Small) H.J.P.Winkler (1931: 116) . ( Fig. 6a ).

Type:— UNITED STATES OF AMERICA. Texas : Laredo, Reverchon 3776 (originally cited as Bush 3776) (holotype NY!, isotypes MO, US!) .

Cathartolinum elongatum Small (1907f: 82) .

Description: — Herbs, annual, occasionally perennial, 15–30 cm in height, glabrous, root thick; stems erect to ascending, striate, branched from the base, branches diffuse, glabrous. Leaves entire, sometimes glandular, alternate, linear, 5.0–25.0 × 0.5–1.0(1.5) mm, sessile, apex acute; 1-nerved, nervation more evident in the abaxial surface, scariose; glabrous, stipular glands present, sometimes only at the base of distal leaves. Inflorescence a cymose panicle, pedicels 5.2–10.4 mm long; bracts 3.2–6.3 mm long, margin dentate, apex acuminate, with stipular glands present at the base; sepals deciduous, lanceolate, 6.0–11.0 × 1.4–1.8 mm, margin glandular-dentate, apex attenuate, 3-nerved, stipular glands absent; petals yellow-orange to salmon or brownish-red, wine-red base, widely obovate, 14.0–18.0 mm long; stamens 5.0–6.0 mm long; anthers 1.5–2.5 mm long, brick-red; staminodia absent; styles fused to near the apex, 7.0– 9.5 mm long; stigmata capitate, gray to wine-red. Fruit ovoid, yellow, 4.0–4.3 × 3.0– 3.7 mm, glabrous, pericarp thick, apex obtuse, dehiscent into 5 segments; seeds narrowly elliptical, reddish-brown, 2.3–3.0 × 1.2–1.3 mm.

Distribution: — United States of America; in Mexico, in Tamaulipas ( Fig. 5b ).

Habitat and ecology: —Thorny shrubland. Elevation 0–300 m. Compact sandy soils, Xerosol type.

Phenology: —Flowering in February–May; fruiting in March–August.

Note: —In its habitat, during the flowering period, the species is easily recognized due to the color of its petals with their distinctive wine-red-colored band near the center, brick-red anthers and wine-red to gray stigmata, which together provide diagnostic characters. The stems of the species are strongly striate.

Conservation status: — Linum elongatum is known only from a narrow area of Texas and northern Mexico. One locality is known from Mexico, in the state of Tamaulipas, which may suggest some vulnerability. With only these data, it is not possible to carry out a conservation assessment. Therefore, to explore its probable threat category, it was necessary to integrate the records of GBIF. According to the B criterion ( IUCN 2019), this species is Near Threatened (NT). Thus, it presents an EOO close to 20,000 km ² (22,940.563 km 2) and AOO <2000 km ² (116 km 2), and although only one locality is known in the country, according to the data found in GBIF it is likely that it is found in ≥ 10, so some degree of uncertainty is added.

Specimens examined: — MEXICO. Tamaulipas: Nuevo Laredo, Along Hwy 2, 5 mi E of junction with Hwy 85, 28 August 1976, C.M. Rogers 13477 ( CIIDIR!) .

Figures

FIGURE 5. Geographic distribution in the Mexican territory of:A. L. cruciata, L. lasiocarpum, L. lewisii, L. mexicanum, and L. tenellum; B. L. elongatum, L. neomexicanum, L. puberulum, L. rzedowskii, and L. schiedeanum; C. L. modestum, L. orizabae, L. pringlei, L. scabrellum, and L. vernale. Maps by Ma. Isabel Olivares.

FIGURE 6. A. Linum elongatum; B. Linum flagellare; C. Linum lasiocarpum; D. Linum lewisii. Photographs by José Luis Colin.