朱砂根和红凉伞花器官的形态补充描述

Supplementary Description of Floral Morphology of Ardisia crenata and A. crenata Sims. var. bicolor(Primulaceae)

朱砂根和红凉伞在最新的分类系统中均隶属于报春花科(Primulaceae)紫金牛属(Ardisia)植物,由于二者在植株形态上存在过渡性状,从而缺乏明显的区分界限,而花部形态是属下划分及种间界定的关键性状,具有较高的分类价值,因此,基于对二者原始形态描述的基础上,分别对其花器官形态与解剖结构进行补充,旨在更加准确地掌握它们在形态性状上的差异。结果表明:朱砂根和红凉伞均为圆齿亚属,主要区别在于叶色的过渡,其余形态无太大的差异性,黑色腺点分布于2种植株的所有器官中,具有较高的观赏价值;朱砂根和红凉伞的花序较多,从外到内不断分化,而花序梗随着花芽的分化逐渐伸长;通过石蜡切片解剖发现,朱砂根和红凉伞花芽分化较早,最小采样花序大小为0.5 mm左右,2种植株均处于花芽分化末期,因此,从外观上不能反映其内部的结构变化;朱砂根的子房膨大有2种类型,当横径>纵径时,子房分化为2室,胚珠和花粉粒成熟,易于受精;纵径>横径时,柱头快速突破花冠裂片高于雄蕊,但子房暂未分室,未见花药明显散粉,导致受精失败和柱头脱落;而红凉伞子房横径和纵径同时生长易于受精,座果率略高于朱砂根。此外,二者通常形成2室子房,本研究还发现朱砂根中具有分化为3室的子房,而红凉伞子房则分隔为完整的4室,后期花器官在外部形态发育过程中没有明显的区别,且二者的花芽分化、开花和坐果等物候期持续时间一致,但朱砂根花芽分化早于红凉伞约7~10d,这可能与所处的生境不同有关,结果可为物种鉴定及属内分类修订提供参考依据。

Ardisia crenata and Ardisia crenata Sims. var. bicolor are members of genus Ardisia in Primulaceae in the latest taxonomy systems. There are some transition traits between them which lead to lack of clear interspecific delimitation. Floral morphology is a key trait for subgeneric and interspecific delimitation, which has a high classification value. Therefore, the floral morphology and anatomic structure of the two plants were carried out on the description of the original morphology to further understand the differences of the morphological characters accurately. A. crenata and A. crenata Sims. var. bicolor belong to Subgen. Crispardisia Mez, the main difference of them is transition on leaf color,and the other morphology are not significant, the black glandular spots are distributed in all organs of the two plants which have high ornamental value. There are many inflorescences, the pedicels elongate gradually with flower bud differentiation from outside to inside. It is found by paraffin section anatomy that the flower bud differentiation of A. crenata and A. crenata Sims. var. bicolor are earlier and tinier. We sampled the minimum inflorescences about 0.5 mm,which were all at the end of flower bud differentiation, therefore, the appearance of inflorescence could not reflect the internal structural changes. There were two types of ovary expansion of A. crenata, when the growth rate of transverse diameter was faster than that of longitudinal diameter, the ovary divided into two chambers, the ovules and pollen matured and were easier to fertilize. Conversely, the stigma grew quickly and exceeded the stamen, but the ovary was not divided, and the pollen was not matured, which led to failed fertilization and abscission of stigma. While the ovary and stigma of A. crenata Sims. var. bicolor grew simultaneously and fertilized easily, and the fruit setting was slightly higher than that of A. crenata. Usually, both two plants formed 2-loculed ovary. The ovary was divided into 3 locules in A.crenata, and 4 locules in A. crenata Sims. var. Bicolor. There were no obvious differences of external floral morphology in the later stage, and the duration of phenological stages of the two plants such as flower bud differentiation, blooming and fruit setting were consistent, but the flower bud differentiation of A. crenata was about 7-10 days earlier than that of A. crenata Sims. var. bicolor, which maight be related to the habitats. The result could provide a reference basis for species identification and revision of intragenus classification.