The mode of origin of root buds and root sprouts in the clonal tree Sassafras albidum (Lauraceae)

Abstract

The developmental anatomy of root buds and root sprouts was examined in the clonal tree Sassafras albidum. Root samples from 13 clones that varied widely in age and vigor were sectioned and two types of buds were found, "additional" buds and "reparative" buds. Additional buds form during the early growth of uninjured roots and they perennate by growing outwards in concert with the vascular cambium such that bud traces are produced in the secondary xylem. Reparative buds form de novo in response to senescence, injuries, or other types of disturbance. Reparative buds were found on the roots of seven of the clones, whereas additional buds were found on the roots of all 13 clones. The reparative buds had originated in the proliferated pericycle, where they were subtended by sphaeroblasts, or spherical nodules of wood. Few of the reparative buds were vascularized and none were connected with the vasculature of their parent roots. In contrast, most of the additional buds were vascularized, and the leaf traces of several of the additional buds appeared to be contiguous with the conducting xylem of their parent roots. To determine whether both bud types were functional, 82 field-collected root sprouts and 44 incubation-induced sprouts were sectioned at the root-sprout junction and examined for evidence relating to their mode of origin. None of the sprouts were subtended by sphaeroblasts, but 98% were subtended by bud traces, which indicated that they had originated from additional buds. Although reparative buds were more common than additional buds on some of the root samples, they appear to be dysfunctional at sprouting. Additional buds, on the other hand, are able to sprout both as a normal part of clonal spread and from root cuttings.

The role of root buds in the regeneration of Casearia sylvestris Swartz (Salicaceae) in the cerrado, São Carlos, São Paulo state, Brazil

“…In our study, the spatial distribution pattern of C. sylvestris changed from random to clustered in response to the fire in the area. Some studies have shown that fire events damage plant aerial parts, causing a reduction in the amount of auxin reaching the roots, which in turn stimulates the development of sprouts (Bosela & Ewers 1997, Hoffmann & Moreira 2002, Rodrigues et al 2004. The sprouts from the roots may then lead to a clustered pattern, since the mean distance between a main trunk and its sprouts depends on the energy cost of root production and the presence of spots favorable to their growth (Hutchings 1997).…”

Morfoanatomia e histoquímica de Brosimum gaudichaudii Trécul (Moraceae)

“…28, 29), constituem o principal ou único sistema radicular de manutenção e crescimento dos ramos caulinares. Este mecanismo de propagação parece estar associado à perpetuação de espécies formando populações clonais, conforme observado por Bosela & Ewers (1997), em arvores de Sassafras albidum. Hayashi et al (2001) relataram a presença de brotos caulinares aéreos a partir de raízes longas, localizadas paralelamente à superfície do solo, para algumas espécies arbóreas de um remanescente florestal que sofreu vários incêndios.…”

Root suckering patterns in Populus euphratica (Euphrates poplar, Salicaceae)

“…The resulting sprouts are termed root sprouts, root suckers, or root shoots (Wittrock 1884), and also sucker shoots (Jenik 1994). The buds they originate from are termed root buds (Bosela and Ewers 1997). In this article the term root sucker is being used for newly formed ramets; their associated horizontal roots are called spacers.…”