Comparative studies on the development of embryo and primary root in Commelinales

在大多数被子植物中，主根有外源起源。它的发育不影响任何组织的崩解，因为根帽是由原皮原（胚的最外层细胞层）的周周分裂形成的。一个例外的情况是禾本科植物的第一个胚胎根。它溶解了周围的组织，形成一个空腔，将根冠和最外层的被膜——根茎分开。在薏苡仁胚中，四个根原在一个共同的腔体和一个共同的根茎中依次发育。它们都是内生的，并且它们之间没有结构差异。在牛膝草的胚胎发生过程中，主根的根冠是由皮肤原外源形成的。然而，它后来以一种奇特的方式生长。发芽后不久，根冠外侧区域的一些细胞开始自溶，形成空腔。通过扩大腔将根帽分为内部和外部部分。内层紧贴根体，外层被生长的根体刺穿，最后向外伸展，在下胚轴基部形成小叶状附属物。似乎可以认为这种发展模式介于外源和内源根形成之间。在无菌的营养培养基中培养兰属植物Habenaria和Platanthera胚。对原球茎、不定根和块根进行了形态学和解剖学研究。茎尖的主轴被结节根原基近端包围。然后，块根和茎尖一起，通过茎的一个破洞长出植物体。作者尝试用计算机图形学绘制这些报告的解剖图。但是软件编程还没有完成。他计划在接下来的几年里做更多的报道。

In the majority of angiosperms, the primary root has an exogenous origin. Its development does not effect any tissue disintegration, because the root cap in formed by periclinal divisions of the primary dermatogen, the outermost cell-layer of the embryo. An exceptional case is the first embryonal root of Gramineae. It dissolves the surrounding tissue and makes a cavity which separates the root cap and the outermost envelop, the coleorrhiza. In the embryo of Coix, four root primordia develop successively within a common cavity and a common coleorrhiza. All of them are endogenous and no strctural difference was observed among them.During the embryogenesis of Commlina, the root cap of the primary root is initiated exogenously from the dermatogen. However, it grows later in a peculiar way. Shortly after germination, some cells within the lateral region of the root cap begin to dissolve by autolysis, forming a cavity. By the enlarging cavity the root cap is separated into an inner and an outer part. The inner part adheres to the root body, but the outer part is pierced by the growing root body, finally spreads off and forms an umbraculiform appendage at the hypocotyl base. It seems possible to consider this mode of development to be intermediate between exogenous and endogenous root formation.Embryos of Habenaria and Platanthera (Orchidaceae) were cultivated in sterilized nutritious medium. Protocorms, adventitious roots and tuberous roots were investigated morphologically and anatomically. Shoot apex of the main axis is enclosed by proximal part of the tuberous root primordium. Then the tuberous root grows, together with the shoot apex, out of the plant body through a broken hole of the stem.The author endeavored to draw anatomical figures of these reports by computer graphics. But the sortware programming is not yet completed. He has a plan to make additional reports in the following years.