Morphology and Distribution of Colleters and Crystals in Relation to the Taxonomy and Bacterial Leaf Nodule Symbiosis of Psychotria (Rubiaceae)

Abstract

Earlier investigators established that a finger‐like colleter with elongate axial cells and a palisade epidermis is the standard type in the Rubiaceae. This type, with some variation, also prevails in Psychotria, based on a worldwide anatomical survey of vegetative buds from herbarium specimens of 296 species (about 50 % of total). It is virtually the only type found outside of continental Africa. Among African species, it is most common in subgenus Psychotria, with mostly nodule‐free species. In subgenus Tetramerae, with only leaf‐nodulated species, there is a strong tendency toward brushlike and dendroid colleters in which epidermal cells are extremely elongate and separated from each other. It is speculated that this change in colleter morphology associated with presence of nodule bacteria may be correlated with a change in secretion product more suitable for support of bacteria. Three morphological forms of crystal occur: raphides, styloids, clustered crystals. They may occur singly or in combination. Several patterns and trends were noted in crystal distribution that could be of taxonomic significance.

Colleters in Caryocar brasiliense (Caryocaraceae) ontogenesis, ultrastructure and secretion

“…The colleters in C. brasiliense stipules are similar to the "Standard" described by Lersten (1974). "Standard" type colleters are finger shaped, with a short peduncle and a long secretory head, as found in this study.…”

Colleters in Chamaecrista (L.) Moench sect. Chamaecrista and sect. Caliciopsis (Leguminosae-Caesalpinioideae): anatomy and taxonomic implications

“…Standard type colleters are comprised of a secretory palisade epidermis covering a non-secretory central axis, which may or may not be vascularized with xylem and phloem (Lersten 1974). In contrast to this standard type of colleter, which has been described for other botanical families (Appezzato-da-Glória & Estelita 2000;Paiva & Machado 2006a;Vitarelli & Santos 2009), the most common type of colleter for the genus Chamaecrista, as shown by our data along with data provided by Coutinho et al (2015), are comprised of homogenous cells.…”

“…Although Lersten (1974) pointed out that the standard type of colleter is the most widespread, variation in the morphoanatomy of these structures has since been observed such that now several different types of colleters are recognized (Mayer et al 2011;Silva et al 2012;Coutinho et al 2015). Standard type colleters are comprised of a secretory palisade epidermis covering a non-secretory central axis, which may or may not be vascularized with xylem and phloem (Lersten 1974).…”

“…There are several types of colleters, which may originate from protodermal cells only or from all primary meristems (Lersten 1974;Thomas 1991;Appezzato-da-Glória & Estelita 2000;Rio et al 2002;Silva et al 2012;Coutinho et al 2015). Therefore, to properly evaluate the presence of colleters in plants, their morphoanatomy, position and both time and composition of the secretion must be considered in order to avoid erroneous interpretations since such structures share morphoanatomical similarities with other secretory structures (Solereder 1908;Inamdar et al 1986;Subramanian et al 1989;Thomas 1991;Coutinho et al 2015).…”

Morfoanatomia de folha e caule de Genipa americana L., Rubiaceae

“…Todas as espécies de Rondeletia estudadas por Kocsis et al (2004) apresentaram exclusivamente areia cristalina, para T. formosa relataram-se apenas drusas (Coelho et al, 2006), enquanto que ráfides de oxalato de cálcio foram verificadas em P. longepedunculata (Pereira et al, 2003). Apesar de ráfides serem comuns para a família, segundo Lersten (1974), essas formações não foram confirmadas na espécie em análise. Houve o registro de areia cristalina simultaneamente a drusas de oxalato de cálcio para o gênero Genipa (Metcalfe & Chalk, 1950), em concordância com a constatação feita nesta investigação.…”