Trichome complement of Turnera and Piriqueta (Turneraceae)

Abstract

The indumentum of Piriqueta and Turnera is made up of nine different types of trichomes, which broadly can be divided into glandular and non-glandular. Taking into account foot shape, head size and pedicle size, five variants of glandular trichomes are recognized: microcrapitate, stipitate-capitate, sessile-capitate and setiform. The non-glandular trichomes can be simple (unicellular or pluricellular-uniseriate), stellate or porrect-stellate. The setiform glandular hairs are present in most species of Piriqueta. Simple unicellular hairs are the most widespread type, frequently being found in combination with other trichomes. Stellate trichomes show a restricted distribution in both genera. Within Piriqueta, section Africana has only simple trichomes, whereas section Piriqueta has also porrect-stellate trichomes; groups of species can be set up according to the presence and type of glandular trichomes. Within Turnera the stipitate-capitate trichomes are exclusive to series Papilliferae; sessile-capitate trichomes are found in series Microphyllae, Annulares and in some species of Salicifoliae; clavate trichomes are found only in series Turnera; setiform glandular hairs are exclusive to T. collotricha, whereas the microcapitate trichomes are widely distributed