从云杉属的畸形珠鳞看珠鳞的演化

EVOLUTION OF OVULIFEROUS-SCALE DEDUCED FROM THE DEFORMATIONAL OVULIFEROUS-SCALE OF PICEA

在云杉属（Ｐｉｃｅａ）畸形现象调查中，发现畸形珠鳞也是常见的一种畸形现象。将畸形珠鳞进行归类、对比、并且做出一个排序：由典型的短枝式珠鳞逐步向正常的鱼鳞状珠鳞过渡。典型的短枝式珠鳞有一个较明显的轴，轴上着生若干枚鳞片，在鳞片的远轴面基部着生孢子囊（胚珠或花粉囊）；过渡形态轴的珠鳞轴逐渐缩短扁化（但并未完全消失），上部的鳞片逐渐变小、数量减少，下部两枚侧生的鳞片逐渐发达，相背扭转方位约９０°，然后剩下的鳞片之间逐步愈合，最终转变为正常的鱼鳞状。作者认为这类珠鳞的畸变是返祖现象，可能在某些方面反映了珠鳞的历史演变过程。

Through the investigation, the authors find that the deformational ovuliferous-scale frequently occurs in the cultivated trees of Picea. The authors compare these deformed ovuliferous-scales, classify and arrange them into an aligment: a gradual transition from typical brief branch to normal ovuliferous-scale. On the typical brief-branch-type ovuliferous-scale, there is an obvious axis, and several scales on the axis, and there is an ovule (or microsporange) on the outside of the scale. On the transitive ovuliferous-scale, the axis gradually reduces (but not disappears), shallow. The upper scales reduce to little or disappear, and the two lower side scales have gradually revolved about 90° in the opposite direction. The retained scales are healed to normal as the scale or carp. The authors consider that the distortion perhaps is atavism. Perhaps these transitions reflect the developmental process of the ovuliferous-scale in history.