Euploca Nutt., Trans. Amer. Philos. Soc., ser. 2, 5: 189. 1836.

Rueangsawang, Kanokorn & Chantaranothai, Pranom, 2023, A taxonomic synopsis of Heliotropiaceae and new combinations in Heliotropium from Thailand, PhytoKeys 232, pp. 189-210 : 189

Euploca Nutt., Trans. Amer. Philos. Soc., ser. 2, 5: 189. 1836.

Heliotropium [unranked] Orthostachys R.Br., Prodr. Fl. Nov. Holland.: 493. 1810. Type species: Heliotropium foliatum R.Br.

Preslaea Mart., Nov. Gen. Sp. Pl. 2: 75. 1827, nom. illeg.

Heliotropium sect. Orthostachys (R.Br.) G.Don, Gen. Syst. 4: 361. 1838. Type species: Based on Heliotropium [unranked] Orthostachys R.Br.

Schleidenia Endl., Gen. Pl.: 646. 1839. Type species: Preslaea paradoxa Mart.

Orthostachys (R.Br.) Spach, Hist. Nat. Vég. 9: 32. 1840. Type species: Based on Heliotropium [unranked] Orthostachys R.Br.

Hilgeria Förther, Sendtnera 5: 132. 1998. Type species: Hilgeria hypogaea (Urb. & Ekman) Förther.

Type species.

Euploca convolvulacea Nutt.

Description.

Annual herbs. Leaves petiolate or sessile; lamina linear to ovate, apex acute to obtuse, margin entire or revolute, pubescent to strigose or silky silver hairs on both surfaces. Inflorescences terminal or axillary, spike-like, scorpioid or subcapitate cymes, bracteate. Flowers 5-merous. Calyx 5-lobed, lobes linear to lanceolate. Corolla white with a yellow-orange throat inside, tubular or funnel-shaped, lobes orbicular to oblong, throat pubescent inside. Stamens included, sessile or with short filaments; anthers, elliptic-oblong. Ovary divided into 4 lobes. Fruits separating into four 1-seeded nutlets.