Damián, Karremans & Pupulin & Damián-Parizaca, 2025

3. Vanilla subgen. Membranacea Karremans , Pupulin & Damián , subgen. nov.

Type species:— Vanilla mexicana Miller (1768 View in CoL : without page number).

= Vanilla subsect. Membranaceae Portères (1951: 291) , nom. inval. nud. (Art. 39.1; Turland et al. 2018).

= Vanilla subsect. Membranaceae Portères (1954: 159) , nom. inval. nud. (Art. 39.1; Turland et al. 2018).

Diagnosis:—Nomadic vines, with one terrestrial species retaining a juvenile growth habit ( V. dietschiana ). Stem smooth, scandent, branched, terete, non-sulcate, succulent. Leaves sub-petiolate to sessile, membranaceous, sub-reticulate, developing conspicuous blades, rarely reduced. Inflorescences axillary, racemose, often with leaf-like bracts, developing either on the proximal or distal part of the stem. Ovary non-calyculate. Flowers resupinate, long-lived, produced in succession, slightly fragrant. Sepals and petals green, often dark or coppery green. Lip white, typically with salmon, pink, green or yellow markings especially on the keels, calli, and warts. Sepals free, spreading, mostly contorted and undulate, smooth. Petals free, dorsally sulcate, spreading, mostly undulate-contorted. Lip sessile or with a very short claw, fused to the column only at its base, simple to trilobed, midlobe often quite distinct, disc often with two large longitudinal lamellae, thickened cushion-like calli, or with narrow to thickened-rugose longitudinal keels, lacking a penicillate callus. Column short, about half the length of the lip, arched, in a few species with a short to long foot. Pollen in monads, forming two easily disrupted masses. Fruit cylindrical, mostly straight, bean-like, dehiscent, green, turning black when mature, never yellow or reddish, with a sweet-grassy or putrid, non-vanillic fragrance.

Discussion:—This subgenus of 17 species previously included what was the type of genus, V. mexicana . With the genus now being conserved with V. planifolia as type species instead, the membranaceous Vanilla are no longer the typical subgenus and require a subgeneric name. We propose Vanilla subgen. Membranacea , using the name originally used for this group by Portères. It is here divided into two sections, the broadly distributed Vanilla sect. Membranacea (11 spp.) featuring species with predominantly distal inflorescences and allogamous reproduction, and Vanilla sect. Dictyophyllaria (6 spp.) which is primarily distributed in the Atlantic Forest and bears mostly proximal inflorescences and autogamous reproduction. Both sections have consistently received strong support in phylogenetic studies, including our own analysis ( Fig. 1 View FIGURE 1 ) and the recent comprehensive phylogenomic reconstruction by Damian et al. (2025b).