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．