Instituto de Botánica del Nordeste (UNNE-CONICET), Sargento Cabral 2131, C. C. 209, C. P. 3400, Corrientes, Argentina.
Facultad de Ciencias Exactas y Naturales y Agrimensura (FaCENA-UNNE), Avenida Libertad 5470, C. P. 3400, Corrientes, Argentina.
Protoplasma. 2022 Mar;259(2):237-261. doi: 10.1007/s00709-021-01664-8. Epub 2021 May 15.
Information on the reproductive anatomy in genera of the tribe Naucleeae, particularly Cephalanthus, is scarce and fragmented. Of the six species in the genus, only the mature megagamethophyte of Cephalanthus occidentalis has been described. This study aims to provide information on embryological aspects in flowers of C. glabratus and to analyze the morphology and anatomy of the flowers, fruit, and seed in the six species of the genus. Cephalanthus glabratus have imperfect flowers: pistillate (PF) and staminate (SF). In the PF, the ovules are functional, while in the SF, they atrophy during the formation of the embryo sac. The mature ovule has a single integument, corresponds to the Phyllis type and the embryo sac is a Polygonum type, forming only in the PF. The presence of pollenkitt and secondary presentation of pollen were observed in the SF, as well as in the pollen formation previously described, whereas in the PF, they are absent, due to the collapse of the pollen grains inside the indehiscent anthers. The analysis of the ontogeny of the ovular excrescence in C. glabratus determined its funicular origin, calling it an aril. Its development is a pre-anthesis event, initiated during megasporogenesis. In seeds, the aril is a fleshy, white appendage which almost completely envelops the seeds of Cephalanthus, except for Cephalanthus natalensis where it is noticeably more reduced. Studies of the fruit in Cephalanthus species indicate that the infructescence is a dry schizocarp which separates into uni-seminated mericarps, except in C. natalensis that has fleshy indehiscent fruit.
关于 Naucleeae 族属植物生殖解剖学的信息，尤其是 Cephalanthus，十分匮乏且零散。在该属的六个物种中，只有 Cephalanthus occidentalis 的成熟大配子体被描述过。本研究旨在提供 Cephalanthus glabratus 花的胚胎学方面的信息，并分析该属六个物种的花、果实和种子的形态和解剖结构。Cephalanthus glabratus 为不完全花：雌花（PF）和雄花（SF）。在 PF 中，胚珠是有功能的，而在 SF 中，胚珠在胚囊形成过程中萎缩。成熟胚珠有一个单一的珠被，对应 Phyllis 型，胚囊为 Polygonum 型，仅在 PF 中形成。在 SF 中观察到花粉粒上有花粉粒胶和花粉粒的二次出现，以及之前描述的花粉形成，而在 PF 中，由于花粉粒在不开裂的花药内崩塌，花粉粒不存在。在 C. glabratus 中，胚珠赘生物的发生分析确定了其珠柄起源，称之为假种皮。其发育是一个在大孢子发生之前发生的事件。在种子中，假种皮是肉质的、白色的附属物，几乎完全包裹着 Cephalanthus 的种子，除了 Cephalanthus natalensis，其假种皮明显更小。对 Cephalanthus 属果实的研究表明，果序为干燥的蓇葖果，分离成单粒瘦果，除了 Cephalanthus natalensis，其果实为肉质不开裂的。
