Seed Geometry in the Vitaceae

Abstract

The Vitaceae Juss., in the basal lineages of Rosids, contains sixteen genera and 950 species, mainly of tropical lianas. The family has been divided in five tribes: Ampelopsideae, Cisseae, Cayratieae, Parthenocisseae and Viteae. Seed shape is variable in this family. Based on new models derived from equations representing heart and water drop curves, we describe seed shape in species of the Vitaceae. According to their similarity to geometric models, the seeds of the Vitaceae have been classified in ten groups. Three of them correspond to models before described and shared with the Arecaceae (lenses, superellipses and elongated water drops), while in the seven groups remaining, four correspond to general models (waterdrops, heart curves, elongated heart curves and other elongated models) and three adjust to the silhouettes of seeds in particular genera (heart curves of Cayratia and Pseudocayratia, heart curves of the Squared Heart Curve (SqHC) type of Ampelocissus and Ampelopsis and Elongated Superellipse-Heart Curves (ESHCs), frequent in Tetrastigma species and observed also in Cissus species and Rhoicissus rhomboidea). The utilities of the application of geometric models for seed description and shape quantification in this family are discussed.

Geometric Models for Seed Shape Description and Quantification in the Cactaceae

“…To allow the modification of each semi-ellipse separately, as was done for the Vitaceae [35] The models were based on the Archimedean spiral with equation, in the following polar coordinates:…”

“…To overcome these problems, the morphological description of seeds based on the comparison of seed images of defined orientation with geometric models defined by algebraic equations was proposed [22,23]. Morphological descriptions based on geometric models have been applied to seeds in diverse genera and families [24][25][26][27][28][29][30][31][32][33][34][35][36][37].…”

“…A series of geometric models have been described also for the Arecaceae and the Vitaceae [34,35]. In the Arecaceae, the seeds correspond to the following models: circular, elliptic, oval, lemniscate, superellipse, cardioid and derivatives, lenses, and waterdrops [34].…”

“…Some of these types were also observed in the Vitaceae, in particular lenses, superellipses, and waterdrops, while diverse types of waterdrops and heart curves, obtained by the modification of equations of an ellipse, are characteristic of genera and species in this family. The models obtained were adjusted with precision to the shape of seeds in genera and species of this family [35].…”

New Geometric Models for Shape Quantification of the Dorsal View in Seeds of Silene Species

“…Departing from studies in the model plants Arabidopsis thaliana (L.) Heynh., Lotus japonicus (Regel) K. Larsen, and Medicago truncatula Gaertn [ 4 , 5 , 6 ], morphological descriptions based on geometric models have been applied to seeds in diverse taxa and families, such as Capparis spinosa L. (Capparaceae) [ 7 ], Rhus tripartita (Ucria) Grande (Anacardiaceae) [ 8 ], Jatropha curcas L. and Ricinus communis L. (Euphorbiaceae) [ 9 , 10 ], as well as Triticum aestivum L. (Poaceae) [ 11 ]. Reviews of seed morphology based on this method have been applied to the families Arecaceae [ 12 ], Cactaceae [ 13 ], and Vitaceae [ 14 ], and general overviews of the subject were presented in the orders Cucurbitales [ 15 ], and Ranunculales [ 16 ].…”