ジョンコン材の放射状材内師部ストランド

Abstract

ジョンコン材の放射状材内師部ストランドを構成する細胞要素を調べ, 師管要素, 繊維, 柔細胞ストランドおよび不定形の柔細胞をみとめた。師管要素は複師板をもち, その構造は通常の二次師部の師管要素の師板の構造によく似ていた。繊維の多くは薄壁であったが厚壁のものもみとめられた。これらの要素は放射方向に配列し, 師管と繊維は師部ストランドの内方にそれぞれ群をなし, その外側に柔細胞がみとめられた。不定形柔細胞は師部ストランドの外側を包み, 特に上下両縁に多くみとめられた。

Jongkong wood contains the included phloem in radial strands. Cellular elements in the phloem strands were investigated and four types of cells could be recognized in the macerated phloem strands: (a) sieve tube members with compound sieve plates, (b) fibers, most of them were thin-walled (probably immature) but occasionally thick-walled ones were present, (c) parenchyma strands, composed of cells with pitted wall, (d) parenchyma cells, not pitted, variable in form but mostly elongated. The compound sieve plates in the phloem strands resembled those observed in the ordinary secondary phloem. In the phloem strands sieve tube members and fibers were in the center of the strand, and were surrounded with parenchyma cells. Parenchyma cells having variable forms were considered the conjunctive tissue. An observation on the origin of the radial phloem strands suggests that small gaps were sporadically formed in xylem by local cessation of xylem formation and filled with the conjunctive tissue and phloem elements radially rearranged.