Contributions of leaflet anatomy to the distinction of two species of Ceiba Mill. (Malvaceae - Bombacoideae): Ceiba pubiflora (A. St.-Hil.) K. Schum. and Ceiba speciosa (A. St.-Hil.) Ravenna

Ceiba is a genus of tree species with a predominantly neotropical distribution which, in general, are readily recognized in the landscape in the vegetative stage by their large trunk with prickles, commonly ventricose (swollen). Some Ceiba species have overlapping geographical distributions, such as C. speciosa and C. pubiflora. These species have quite uniform vegetative features, making it difficult to differentiate them when they are not in flowering. Here, we examined the leaflets anatomical features of the two species in order to distinguish them while in the vegetative phase. Fully expanded leaves were collected, fixed, embedded in paraffin and cross-sections were made from the leaflets midvein, margin and intercostal region. Ceiba speciosa has hypostomatic leaflets, with continuous biseriate epidermis along the adaxial face, rectilinear margin with a vascular bundle at the end of the margin while Ceiba pubiflora has amphistomatic leaflets, with interrupted biseriate epidermis along the adaxial face and curved margin on the abaxial face. These taxonomically important anatomical features of C. speciosa and C. pubiflora leaflets have provided additional characters good for distinguishing the species especially when they are in the vegetative phase; and therefore updates the existing accounts of the characters useful for the taxonomy of Malvaceae.