竹节解剖构造的研究

ON THE NODAL STRUCTURE OF BAMBOO

对6种竹子节的解剖构造进行了观察,并将节部的构造与节间的构造进行比较。在节部,维管束大量分叉,形成复杂的网络系统。象竹秆节间中那样的典型的维管束结构消失了。维管束的侧鞘通常发育很差或不发育;丛生竹维管束两极的分离纤维束不复存在。原生木质部的侵填体不仅发生在散生竹类,而且也发生在丛生竹类。后生木质部已不再有2个大型的导管组成,而由大量的大小不等的导管组成。为了适应水分及养分的横向转运,原生木质部的导管常具分叉,后生木质部的导管则具多个穿孔;韧皮部筛管分子的侧壁上分布了大量筛域,在韧皮部分叉处,大量细长的线形韧皮薄壁细胞形成纺锤体状的迭生构造。基本组织细胞的形态极不规则。纤维的平均长度要较节间内的短得多,其尾端通常圆钝,有时具长的分叉,部分纤维细胞内有内含物。通过连续切片的观察,重建了维管束在节部的分布模式。

Study on the nodal anatomic structure of 6 bamboo species in coraparision with the structures of internodes showed that the typical vascular bundle structure of bamboo disappears. There are no differences between pachymorph and leptomorph species. The lateral fibre cap is often absent or only weakly developed, and the isolated fibre strands in pachymorph bamboos is absent. Intensive branching of vascular bundle is common in the nodal region. The composition of vascular bundle is partly changed. At the branching of the vascular bundles the metaxylem consists of many small vessels which are arranged in 'V' form. Some of them are deformed with more perforations. The protoxylem vessel branching is common. Some of them appear forked with long branches. They can be filled with only few large tyloses. The sidewalls are covered with more sieve areas. At the branching point,one type of special phloem, elements link the phloem of the main vascular bundles with those in branched subordinate vascular bundles. These special cells are filiform with a diameter of only 5μ and a length of about 140μ they build a spindle bundle structure and arranged in a storied-like pattern with three to five subunit. Based on the serial sections, a perspective of the three-dimensional structure was reconstructed.