Fruit Anatomy of the Canarieae (Burseraceae).

María C Martínez-Habibe

doi:10.3390/plants11030253

Abstract

Fruits historically have been the key character for delimitation of tribes in the Burseraceae. However, fruit structure is incompletely known within the family, thus the importance of this character is unclear. This study of fruit anatomy in the traditional tribe Canarieae examines the distribution of the tissues that correspond to the exo-, meso-, and endocarp. The detailed arrangement and measurement of the tissues are reported here for the first time in all eight genera in the tribe. The evidence suggests that in all cases except Pseudodacryodes, the endocarp has at least one layer of parenchyma cells within which a sclereid layer is evident and, in some cases, an inner epidermis. All Canarieae fruits exhibit secretory canals, and some taxa have epidermal glands with resin-like contents. Evidence of carpellar sutures was found for all Canarieae, and in Dacryodes, Haplolobus, Rosselia, and Santiria, an articulated plate is present that corresponds to an abortive locule. The anatomical and morphological characters presented here are useful in delimiting genera within Canarieae.

Highlights

IntroductionInfrafamiliar classification of Burseraceae historically has been defined primarily by fruit characters, especially the degree of connation of the pyrenes (a pyrene is a seed with bony endocarp) in the compound drupe
Infrafamiliar classification of Burseraceae historically has been defined primarily by fruit characters, especially the degree of connation of the pyrenes in the compound drupe
Current Burseraceae tribes are these: Protieae, with fruits dehiscent and pyrenes free or connivent but separable, the mesocarp and pericarp usually carnose or sometimes dry; Boswellieae (=the autonym Bursereae), with fruits dehiscent consisting of pyrenes more or less connate but usually detachable from each other or separating when mature, the mesocarp and pericarp dry and dehiscent; and Canarieae, with fruits indehiscent and pyrenes more or less and often entirely connate, always forming a plurilocular putamen, pericarp carnose, rarely more or less dry

Summary

Introduction

Infrafamiliar classification of Burseraceae historically has been defined primarily by fruit characters, especially the degree of connation of the pyrenes (a pyrene is a seed with bony endocarp) in the compound drupe. In the tribe Canarieae, the most important of those references is Lam’s description of a three-winged bony axial “intrusion” in the fruit of Canarium [6], a characteristic Lam considered important enough to divide Canarieae into two subtribes based on the presence or absence of the intrusion. Another contribution to fruit structure in Canarieae was Cuatrecasas’s work on Neotropical Dacryodes, where he described “carpelar sutures” in the fruit [7] and an endocarp with “only one seminiferous cavity and one tiny, appressed sterile cell” [8]. The sterile cell has been used as part of the description of a New World species of Dacryodes as an articulated plate [9]

Methods

Results

Conclusion