Endress Peter K
Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, 8008 Zurich, Switzerland.
Ann Bot. 2005 Aug;96(2):209-15. doi: 10.1093/aob/mci174. Epub 2005 May 31.
The morphological structure of anthetic carpels of Brasenia (Cabombaceae), a member of the phylogenetically basal ANITA grade, has not been studied before. The carpel has a long stigmatic crest on the ventral side and could give the impression of a conduplicate structure. This is in contrast to the carpel structure in other genera of the ANITA grade. Therefore, a study of carpel development and carpel structure at anthesis was carried out.
Carpels of Brasenia schreberi were studied at different developmental stages up to anthesis by means of microtome section series and SEM to analyse and reconstruct the outer and inner carpel morphology.
Carpels of Brasenia are extremely ascidiate up to anthesis. The elongate stigma originates around the mouth of the young carpel, which is slightly curved toward the centre of the flower. Subsequently, the stigmatic zone below the mouth expands by massive intercalary elongation.
In their ascidiate shape, carpels of Brasenia are similar to carpels of Cabomba, the other genus of Cabombaceae, which, in contrast, has a short stigma restricted to the tip of the carpel. Thus, the morphological structure is independent of the extent (and one-sidedness) of the stigma. The outer shape of carpels at anthesis does not allow the inference of the inner morphological surface. If an angiosperm carpel has a one-sided stigma it can be extremely conduplicate or extremely ascidiate. Therefore, caution has to be used in the interpretation of the structure of fossil carpels.
莼菜（莼菜科）是系统发育基部ANITA等级的成员，其开花期心皮的形态结构此前尚未被研究过。心皮腹面有一条长长的柱头嵴，可能会给人一种对折结构的印象。这与ANITA等级其他属的心皮结构不同。因此，开展了一项关于心皮发育和开花期心皮结构的研究。
通过切片系列和扫描电子显微镜对莼菜不同发育阶段直至开花期的心皮进行研究，以分析和重建心皮的内外形态。
莼菜的心皮在开花期前极度呈囊状。细长的柱头起源于幼小心皮的口部周围，口部略向花的中心弯曲。随后，口部下方的柱头区域通过大量居间伸长而扩展。
莼菜的心皮呈囊状，这与莼菜科的另一个属水盾草的心皮相似，相比之下，水盾草的心皮柱头短，仅限于心皮顶端。因此，形态结构与柱头的长度（和单侧性）无关。开花期心皮的外形无法推断其内部形态表面。如果被子植物的心皮有单侧柱头，它可能极度对折或极度呈囊状。因此，在解释化石心皮的结构时必须谨慎。
