双子葉植物の胚の初期分化の様式と系統
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In the early stages of development of embryo in the Dicotyledons, some features seem to be characteristic to indicate the phylogenetic differentiation. Among them, the most reliable feature is in the patterns of differentiation in the initials of root-cortex, which is usually constant within the families, or even within the orders in some cases. Based on this feature, five types are recognized for the embryos of the Dicotyledons : 1) Polygonad type. (Fig. 1, I). The hypophyse cells iec are derived from the lower central cells of the tier m which consists of many cell-layer being derived from the upper part of the basal cell cb in two-celled stage. The upper cells of this tier give rise to the lower part of the hypocotyl. (Based on Polygonum persicaria, SOUEGES 1919). 2) Solanad type. (Fig. 1, Ii). The cells iec are derived from the lower central cells of the tier cd or its derivative in early stage. The upper cells of this tier give rise to the hypocotyl. (Based on Nicotiana sp., SOUEGES 1920b). 3) Geraniad type. (Fig. 1, III ; Fig. 2). The tier m consists of three or more cell-layers being derived from the upper part of the basal cell cb of two-celled stage. The cells iec are derived from the upper central cells of the tier m. The lower cells of this tier give rise to the root cap and a part of the suspensor. (Based on Geranium molle, SOUEGES 1923). In many instances the tier m consists of two cell-layers, in which the central cells of the upper layer give rise to the hypophyse cells and the lower layer to the root cap. This form is named as the Myrtus variation. (Based on Myrtus communis, SOUEGES 1940). 4) Asterad type. (Fig. 1, IV). The tier n (or m) consists of one cell-layer. The central cells of this layer give rise to the hypophyse cells. This form is generally accompanied with α and β cells which are produced by diagonally oriented divisions in the tier ca with four cells in eight-celled stage. (Based on Senecio vulgaris, SOUEGES 1920c). In some instances, the tier m consists of two or three cell-layers, in which the hypophyse cells are derived from the upper layer and the root cap from the lower ones. This form is named as the Calendula variation. (Based on Calendula officinalis, MESTRE 1964). 5) Onagrad type. (Fig. 1, V-B). The apical part of the cell m inserts in the upper tier cd. A transverse wall lays down in the apical part to cut off a lenticular cell at the apex, which is followed by twice longitudinal divisions to produce the four-celled hypophyse. (Based on Oenothera biennis, SOUEGES 1920a). In some instances (Clusiaceae, Crassulaceae, Campanulaceae, etc.) the hypophyse cells are derived from the tier cd which consists of the lower daughter cells derived from the upper cell ca of two-celled stage. In the other instances (Rosaceae) the hypophyse cells are derived from the tier n consisting of the middle daughter cells of the basal cell cb. However, the hypophyse cells formations of these two types are essentially similar to that of the Onagrad type. In Ruta variation (Fig. 1, V-A), the hypophyse cells are produced by two longitudinal divisions at first and followed by transverse or diagonal ones at the tier m. Thus formed, hypophyse cells are essentially similar to that of the Onagrad type. (Based on Ruta glaveolens, SOUEGES 1926). In some instances as Dipsacaceae, Piperaceae, Tiliaceae, Buxaceae, etc. earlier development of the embryo is followed by irregular cell division. Therefore, it is difficult to distinguish the types of embryonic development and named as the irregular type. However, some irregular types may be recognizable in comparison with those of the regular types of the related species. The Solanad type has the same behavior as the Polygonad type, in which the hypophyse cells and the hypocotyl are derived from the same tier. The former type seems to be a specialized form of the latter. The onagrad type has the same behavior with that of the Geraniad type, in which the hypophyse cells and the
- 日本植物分類学会の論文
- 1982-04-20