midvein

1. The prothallium has no trichome but thick midvein, large antherid and archegonium. However, O.
   原叶体无毛状体，中脉厚，精子器和颈卵器较大；
2. The sori are borne on the abaxial surface of the pinnule, arranged in two rows parallel to the midvein, elliptic, and composed of 4-10 round sporangia.
   囊群椭圆形，由4～10个孢子囊组成，着生于小羽片背面，位于中脉的两侧；
3. Stomatal apparatus are oval, and the long axes of stomata are perpendicular or oblique to the midvein of the leaves in Taxodium, and oblique to the midvein of the leaves in Cryptomeria, mostly parallel to the midvein of the leaves in other genera of Taxodiaceae.
   气孔椭圆形，落羽杉属植物的气孔长轴方向与叶片长轴垂直或斜向排列，柳杉属植物的气孔多斜向排列。落羽杉属和柳杉属以外的杉科植物的气孔长轴多数与叶片长轴平行。
4. Stomatal apparatuses are oval, and the long axes of stomata are mostly perpendicular or oblique to the midvein.
   气孔器椭圆形，长轴与叶片长轴垂直或成一定的角度。
5. The origin of the midvein calli developed mainly from the vascular cylinder, the palisade tissues and the phloem parenchyma cells.
   主脉的愈伤组织主要由维管束鞘薄壁细胞，以及与其邻接的一些栅栏组织细胞和韧皮部的薄壁细胞分裂而来。
6. Stomatal band comprises 4-8 lines of stomata on each side of the midvein on the abaxial surfaces of the leaves.
   叶片远轴面气孔分布于中脉两侧，每侧各有4-8列气孔。
7. In order to deal with the problem that the traditional methods can not handle leaf models, we first analyze the shapes of leaves. Then we extract, sift and match the feature points of the boundary and midvein curves, based on the symmetric and geometric information.
   针对传统参数化方法难以处理叶片模型的问题，从分析叶片的形状出发，充分利用其对称性和几何信息，对边界和主脉曲线上的特征点进行提取、筛选和匹配。
8. The anatomical structure of midvein of Quercus mongolica in the middle part of leaf, the greater the intensity of the light, the palisade tissue is smaller.
   蒙古栎叶中脉部位解剖结构中，在蒙古栎叶叶中部，光照越强，叶肉栅栏组织厚度越小。

noun

1. the vein in the center of a leaf

   Synonym:    midrib