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

在大多数被子植物中，初生根具有外源起源。它的发育并不影响任何组织的解体，因为根冠是由初级皮肤原（胚的最外层细胞层）的平周分裂形成的。一个例外的情况是禾本科植物的第一个胚根。它溶解周围的组织，形成一个腔，将根冠和最外层的被膜（coleorrhiza）分开。薏苡的胚在一个共同的腔和一个共同的胚根中先后发育出四个根原基。它们都是内源性的，在结构上没有明显的差异，在Commlina的胚胎发生过程中，初生根的根冠是由表皮原外生的。但是，它后来以一种特殊的方式生长。萌发后不久，根冠侧面区域内的一些细胞开始通过自溶溶解，形成空腔。通过扩大的空腔，根冠被分成内部和外部。内部附着在根体上，外部被生长的根体刺穿，最后散开，在下胚轴基部形成一个伞形附属物。这种发育方式可能介于外源根形成和内源根形成之间。以玉凤花属（Habenaria）和悬铃木属（Platanthera）的胚为材料，在无菌营养培养基中进行培养。对原球茎、不定根和块根进行了形态解剖学观察。主轴茎尖被块根原基近端包围。然后，块根与茎尖一起从茎的破孔中长出植株体外。作者还用计算机绘图绘制了这些报道的解剖图。但软件编程尚未完成。他计划在今后几年提出更多的报告。

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.