螺序草属（茜草科）的种子形态

Seed Morphology of Spiradiclis Bl. (Rubiaceae)

摘要:

对螺序草属(Spiradiclis B1.)16种2变型共18个样品的种子形态特征的初步研究表明，本属植物种子为小型（0.2—0.3 mm)或中型(0.3—2 mm)，整体形状不太规则，表面纹饰为蜂窝状，种脐稍突出。种子的外壁由内外2层种皮组成。依据表面突起分布方式，螺序草属的种子大致分为2种类型：(1)平周壁微下陷，疣突均匀分布于其上，如大叶螺序草、螺序草、尖叶螺序草、柳叶螺序草、峨嵋螺序草和龙州螺序草；(2)平周壁下陷成穴状，突起分布在穴边缘，如红花螺序草、心叶螺序草、两广螺序草、广东螺序草、海南螺序草、宽昭螺序草、疏花螺序草、多枝螺序草、罗氏螺序草、小叶螺序草、石生螺序草和紫花螺序草。螺序草属的种子形态特征对属下类群的划分具有重要的参考价值。

Abstract:

The seeds of 18 taxa including 16 species and 2 forms of genus iradiclis B1．were examined．The seeds ofspiradiclis have small(0．2-0．3 mm) or medium size (0.3-2 mm)，irregular shape，alveolate surface，slightly prominent hilum．Seed testa consists of exotesta and endotesta．The projections on periclinal wall of epidermis cells can be classified into two types：the projections are either distributed consistently on slightly concave periclinal walls，which can be seen in 6 taxa，viz．：S. bifida，S. caespitosa，S. caespitosa f. cylindrca，S. caespitosa f. subimersa，S. emeiensis and S. 1ongzhouensis，or around the fovea formed by deeply concave periclinal walls，which can be found in 12 taxa，viz.：S. coccinea，S. cordata，S. fusca，S．guangdongensis， S. hainanensis，S. howii，S. laxiflora，S．1eptobotrya，S．1oana，S. microphylla，S. petrophila and S．purpureocaerulea．The seed morphology in spiradiclis can play an important role in distingu ishing infra-genus taxa．