Typha×glauca Godr.,香蒲属(香蒲科)中国新记录杂种及其形态特征

香蒲属(Typha L.)为多年生水生或沼生草本植物, 种间存在十分普遍的杂交现象, 其中一些杂种在湿地生态系统中有重要的作用。在查阅大量腊叶标本基础上, 结合野外居群生物学工作, 作者发现中国一新记录杂种, 即T.×glauca Godr. (T. angustifolia L.×T. latifolia L.), 并新拟“粉绿香蒲”作该杂种的中文名。对粉绿香蒲的形态特征进行了研究, 讨论了其与亲本水烛和宽叶香蒲的区别, 并给出检索表。

TYPHA×GLAUCA GODR.,A HYBRID OF TYPHA L. (TYPHACEAE) NEWLY RECORDED IN CHINA AND ITS MORPHOLOGICAL CHARACTERISTICS

Typha L. (Typhaceae), one of the most common aquatic plants found in marshes and shallow water, is almost cosmopolitan. However, the distribution of approximately 24 species has two main centers: Eurasia and North America. To date 12 species have been reported in China. Typha was described by Linnaeus in 1753, and its taxonomy remains confusing because of the variability in its reproductive and vegetative characteristics, and its frequent hybridization. Seven hybrids of Typha species were reported from North America and Europe but none of them has been recorded in China. We have discovered a hybrid cattail, Typha × glauca Godr. (T. angustifolia L. × T. latifolia L.), through extensive field collections and herbarium studies. That was a newly recorded taxon for China. We studied the hybrid T. × glauca in the field and examined Typha collections from the following herbaria including PE, IBSC, CDBI, HIB, WU, SZ, and CCNU. Both vegetative and reproductive characteristics were measured for available specimens of the hybrid and parental species from China. Pollen grains of Typha species were collected from our field collections, and were examined under a light microscope at ×1000 magnification. Morphological features of the hybrid and parental species was illustrated and discussed, and an identification key for them was provided. The hybrid was morphologically variable and generally intermediate to the parental species. The most readily diagnostic features of the hybrid were: 1. leaves were glaucous; 2. pollen was typically a mixture of monads, dyads, triads, and tetrads (vs. tetrads in T. latifolia and monads in T. angustifolia), often abortive; 3. pistillate bracteoles were narrower than the stigma (vs. broader in T. angustifolia and absent in T. latifolia), and 4. the stigmas were liner-lanceolate (vs. linear in T. angustifolia, and lanceolate to ovate-lanceolate in T. latifolia). Importantly, the presence /or absence of dyads and triads of pollen grains could be used to distinguish the hybrid and parental species, implying that pollen morphology is of importance in taxonomic treatment of genus Typha. In North America, Typha × glauca is a well-known cattail hybrid and can occur wherever T. angustifolia and T. latifolia grow together and often out-competes the parental species in habitats that are heavily disturbed or subject to high-magnitude water level fluctuations. The hybrid plants could interfere with wetland communities by forming large monospecific stands, out-competing native species, and altering substrate characteristics, suggesting that the appearance of hybrid plants may be used as indicators of disturbance and, perhaps, of wetland health. After checking the available specimens assigned to either T. angustifolia or T. latifolia that were deposited in the Herbaria of China, we found that T. × glauca was confined to the Xinjiang Province of China. Given the paucity of field collections on Typha plants over the past several decades and thus resultant relatively limited information on the hybrid in China, the distributional range and its ecological role of the hybrid cattail need to be studied further. In summary, we concluded that the field identification characters of the leaves and inflorescences may be used with some degree of reliability to tentatively separate T. × glauca from the parental species, but microscopic floral characters should be used to confirm the identification. To positively identify T. × glauca and parental species microscopic floral characters must be used.