Taxonomical history
The genus Wittrockia was established by Lindman (1891) on the basis of a single specimen, W. superba Lindm. The concept of the genus has undergone a considerable change to arrive at the parameters proposed by Leme (1997; 1998). Lindman (1891) originally associated it to the genus Nidularium Lem., s. lato, and with the genus Bromelia L., using the petals appendages as a distinguishing character. The author also considered Wittrockia as intermediate to Nidularium and Neoregelia L. B. Sm. [then Regelia (Lem) Lindm.], because it didn't have the branched inflorescence with the showy primary bracts of the former nor the simple inflorescence of the latter.
Mez (1894) reduced Wittrockia to the rank of subgenus in Canistrum E. Morren (= subgenus Nidulariopsis Mez). As a subgenus, the circumscription of Wittrockia was expanded to include Canistrum ama%onicum (Baker) Mez [= Nidularium ama%onicum (Baker) Linden & E. Morren ex Lindm.]. According to Mez (1896; 1934), the subgenus Wittrockia was then distinguished from the subgenus Canistrum (= subgenus Eucanistrum Mez) by its high-connate petals versus the free petals in the latter.
Smith (1945) restored the generic status of Wittrockia, arguing that the petals partially connate at their base were enough to distinguish it from Canistrum and Aechmea subgen. Ortgiesia (Regel) Mez. The petal appendages were used in his key to separate Wittrockia from Nidularium and Neoregelia. The concept of the genus was once more expanded by Smith (1952; 1955; 1969) by means of the inclusion of some species currently included in Nidularium and Neoregelia [e. g., Nidularium minutum Mez, N. azureum (L. B. Sm.) Leme, Neoregelia bragarum (E. Pereira & L. B. Sm) Leme]. In their monograph, Smith & Downs (1979) did not modify the conceptual limits of the genus.
The concept of Wittrockia was expanded further by Leme (1989; 1991a; 1991b; 1992; 1995) by the inclusion of species nowadays positioned in Aechmea, Neoregelia and Nidularium. Based on such disparate taxonomic elements, its circumscription became very confusing, based as it was solely on the presence of petal appendages and basal petal concrescence. Such a chaotic conglomeration of elements from Aechmea, Neoregelia and Nidularium could only be compared to Baker's (1889) concept of Karatas Plumier.
When revising the genera of the so called "nidularioid complex", composed by Canistrum, Canistropsis (Mez) Leme, Edmundoa Leme, Neoregelia, Nidularium and Wittrockia), Leme (1997) introduced arguments in favor of the correlation of multiple traits, based on morphological, anatomical, palynological, biogeographic and ecological data, to retrieve the concept of Wittrockia in order to decrease its unduly artificial nature. The isolated individual use of some diagnostic elements (e.g., nidular inflorescence, flower pedicels, petal concrescence, petal appendages) was assigned a relative value, both in weight and importance (Leme, 1998; 2000). This allowed the recognition of the W. superba Lindm., W. cyathiformis (Vell.) Leme and W. gigantea (Baker) Leme as the "core" taxa of the genus (the last two historically assigned to Canistrum), as well as two other more peripheral taxa, W. spiralipetala and W. tenuisepala (Leme) Leme. Species of Wittrockia clearly related...