Tetraglochin, Poeppig, 1833

Cialdella, Ana M. & Pometti, Carolina L., 2017, Taxonomic revision of the genus Tetraglochin (Rosaceae, Rosoideae) and morphometric analysis of its species, Phytotaxa 296 (3), pp. 201-227 : 210

Key to identify the species of Tetraglochin

1. Hypanthium indurated, tetragonal or pentagonal, each angle expanded in a developed wing, with conspicuously irregular margin and densely pubescent surface, or with reduced or absent wings, replaced by conspicuous thorns with pubescent or glabrous surface.....................................................................................................................................................................................................2

-. Hypanthium membranous, papery or coriaceous, winged, with 4–5 wings, mostly well developed, with dentate or entire margin, or hypanthium globose or inflated, angular, each angle very slightly indurated, entire or toothed, sometimes expanded in a reduced wing....................................................................................................................................................................................................3

2. Hypanthium with narrow wings or without them, with conical indurated pricking thorns, up to 3 mm long, longer than the wings width. Upper surface of leaflets glabrous. ................................................................................................................. T. acanthocarpa

-. Hypanthium with (2–)3 developed wings of conspicuously irregular margin, and 1–2 wings reduced to small, non pricking teeth. Upper surface of leaflets hairy. ....................................................................................................................................... T. caespitosa

3. Hypanthium globose, angular, with inconspicuous slightly indurated wings. Plants 0.10–0.30 m tall, not thorny, with short and highly matted branches, shorter than 5 cm ........................................................................................................................... T. inermis

-. Hypanthium conspicuously winged, the wings with entire margin slightly wavy, or deep and irregularly dentate, all wings well developed, rarely one of them narrower or replaced by 1–5 slightly indurated teeth. Plants 0.20–1 m tall, mainly thorny, with spreading branches.............................................................................................................................................................................4

4. Wings of the hypanthium with toothed margin, coriaceous, translucent, with opaque, wide and indurated rays, each ray ending in a sharp tooth at the margin of the wing, these teeth frequently irregular and conspicuous. ................................................ T. cristata

-. Wings of the hypanthium with entire margin, membranous and translucent, or papery and opaque, sometimes slightly wavy.......5

5. Hypanthium papery, opaque, the wings frequently narrower than the fruit.......................................................................... T. andina

-. Hypanthium membranous, translucent, the wings wider than the fruit..............................................................................................6

6. Wings of the hypanthium 2–4 mm wide; hypanthium (4–)5–12 × 5–10(–12) mm. ............................................... T. alata var. alata

-. Wings of the hypanthium 0.5–1.6 mm wide; hypanthium 3–7 × 2–6 mm ...................................................... T. alata var. ameghinoi