胡颓子科2种旱生植物次生木质部的生态解剖学特性

从生态学角度对沙棘和沙枣的木材结构进行对比研究.两树种具有的共同特点为 :生长轮明显,半环孔材,具单穿孔,导管间纹孔交互排列,无分隔木纤维,导管较窄, 环管管胞和纤维状管胞具螺纹加厚,轴向薄壁组织缺失或很少.所选树种明显区别是射线类型、宽度和叠生排列方式:沙棘射线,轴向薄壁组织细胞和导管分子具有明显的叠生排列方式,但沙枣的叠生排列不规则;沙棘射线为异型,1～2列,沙枣射线为同型,2～5列;并且二者之间数量化指标有差异,沙棘导管频率较大,导管分子较短及导管管孔较小,因此V和M值也较小,更能适应干旱环境.两树种导管分子长和纤维长的水平变动不规律,并且树种间和同一树种个体间差异显著.本文最后对该树种的解剖学特征和沙漠环境的适应性进行了讨论 .

Ecological Anatomy Characteristics of Secondary Xylem Cells of Two Xerophytes in Elaeagnaceae

The wood anatomy of Hippophae rhamnoides and Elaeagnus angustifolia were described and compared from an ecological perspective.Both species showed similar wood structure:distinct growth ring boundaries,semi-ring-porosity,simple perforation plate,alternate intervessel pitting,non-septate fibres and helical thickenings are present while axial parenchyma is absent or rarely present.Typical different characters of two species in Elaeagnaceae are ray type and width and storied structure.In H.rhamnoides,there is a distinct storied structure in rays,axial parenchyma cells and vessel elements,but irregularly storied in E.angustifolia.Rays are uni-to bi-seriate,heterogeneous in H.rhamnoides,and 2-5-seriate,homogeneous in E.angustifolia.But there were few quantitative differences observed between them.The vessel frequency is larger,vessel element length is shorter and vessel diameter is much narrower in H.rhamnoides,thus lead to a smaller vulnerability and mesomorphy value,indicating adaptive to xeric conditions.The horizontal variation of vessel element and fibre length along the ring number from pith showed irregular tendency.There are significantly difference in vessel element length and fibre length within trees and between species.Furthermore,the relationships between anatomical features and adaptability to desert environments were discussed.