Morphology and anatomy of developing fruits and seeds of Mammea americana L. (Clusiaceae)

Abstract

Morphological, structural and developmental features of fruits and seeds of Mammea americana L. are here studied, with the purpose to give a proper classification of their fruit and embryo type and to contribute to future taxonomical and ecological studies. The fruit is a berry and the "rind" consists of the exocarp, represented by a periderm with lenticels, and by the parenchymatic mesocarp, with branched secretory ducts and vascular bundles. The edible pulpy is formed by the endocarp, destituted of secretory ducts, and derived from the activity of a ventral meristem, which emerges early in the fruit development. The inner endocarp cell layers undergo a radial elongation and become firmly attached to the testal outer layers. At maturation the endocarp may be released from the rest of the pericarp. The ovules are unitegmic and they turn into unitegmic and exalbuminous seeds. The multiseriate testa consists of thick-walled cells and sclerenchymatous fibers. This last features have carried out to a wrong interpretation that the fruit of this species is a drupe. The embryo is pseudo-conferruminate, with two massive foodstoring cotyledons, rich in starch, firmly attached.Key words: Clusiaceae, fruit, seed, Mammea, anatomy. RESUMO Morfologia e anatomia dos frutos e sementes em desenvolvimento de Mammea americana L. (Clusiaceae)Descreveu-se, detalhadamente, a morfologia e a anatomia dos frutos e sementes, em desenvolvimento, de Mammea americana L., de modo a identificar corretamente o tipo de fruto e de embrião desta espé-cie, bem como contribuir com futuros estudos taxonômicos e ecológicos do grupo. O fruto desta espécie é uma baga, cuja "casca" é constituída pelo exocarpo, representado por uma periderme com lenticelas, e pelo mesocarpo, percorrido longitudinalmente por dutos secretores e feixes vasculares. O endocarpo, desprovido de dutos, origina-se da atividade de um meristema ventral e da epiderme interna do ovário. Suas células posteriormente se alongam em sentido radial, transformando-se na polpa amarelada, comestível, rica em açúcares e fibras, aderida à testa fibrosa. Os óvulos anátropos, unitegumentados originam sementes unitegumentadas e exalbuminosas. A testa multisseriada, constituída por parênquima de parede espessada e fibras esclerenquimáticas alongadas acompanhando os feixes vasculares muito ramificados, confere à semente o aspecto fibroso externo. Esta característica levou à interpretação errônea de que o fruto desta espécie seria uma drupa. O embrião é pseudo-conferruminado e constituído pelos cotilédones carnosos, fusionados.Palavras-chave: Clusiaceae, fruto, semente, Mammea, anatomia.Rev. Brasil. Biol., 60(4): 701-711 702 MOURÃO, K. S. M. and BELTRATI, C. M.

Fruit ontogeny of Garcinia gardneriana (Planch. & Triana) Zappi (Clusiaceae)

“…Th is anatomical aspect was very clear, even without complete ontogenic studies in the older descriptions such as those of Cordemoy (1911), Sprecher (1919), Rao & Kothagoda (1984), and Corner (1976), as well as in the more detailed studies undertaken by Mourão & Beltrati (1995a,b;2000;2001), Marzinek (2009), andCampana et al (2010) as well as in the present work.…”

“…However, in a study of the seeds and germination of Garcinia mangostana, Sprecher (1919) noted that the pulp arises only from the endocarp (to which the seed integument is attached), being very similar to Platonia insignis Mart. and Mammea americana L. as reported by Mourão & Beltrati (1995ab;2000).…”

“…Th ese latter authors also affi rm that the fruits of Rheedia are "bacóide campomanesoídeo", of the subtype with a fl eshy pericarp and a central cavity fi lled with a uniform pulpy tissue whose central portion contains thin locules arranged radially around the seeds which are generally present in small numbers, similar to the Garcinia gardneriana in the present work. Mammea americana (Kielmeyeroideae -Calophylleae) described by Mourão & Beltrati (2000) and Garcinia gardneriana present unitegmic ovules contrary to what was observed by Corner (1976) in Clusiaceae. Judging by the illustrations of Garcinia prepared by Corner (1976), what this author interpreted as the internal tegument corresponds to the nucellus described in the present study for G. gardneriana.…”

“…It is interesting to note that Mourão & Beltrati (1995a;2000) described the development of the pericarp, and especially the endocarp of the berry fruits of Platonia insignis (Clusioideae -Symphonieae) and Mammea americana (Kielmeyeroideae -Calophylleae), as being similar to that of Garcinia gardneriana. However, M. americana presents a peridermal exocarp and the pulp that surrounds the seeds in the two species is purely endocarpic in origin.…”

“…Detailed ontogenic studies of the fruits and seeds of Clusiaceae, however, have showed controversies in terms of the classifi cation of the fruits, as well as doubts about the position of the species in the subfamilies and tribes as discussed by Mourão & Beltrati (1995ab;2000;2001) and have thus not contributed signifi cantly to recent discussions about infrafamily relationships (Gustafsson et al 2002;Stevens 2007aStevens ,b, 2008. Corner (1976) pointed out that there is significant structural diversity among the seeds of the different species of this family and noted that all of the genera and most of the species needed to be more closely examined, mainly due to the diffi culty in obtaining seeds in diff erent stages of development.…”