几种梓属植物花粉形态及分类学意义

梓属(Catalpa),紫葳科(Bignoniaceae),乔木,全世界约13种,分布于美洲及亚洲东部。我国包括引入种共5种及1变型(中国植物志编委会,2005),包括楸树(Catalpa bungei)、灰楸(Catalpa fargesii)、滇楸(Catalpa fargesii f.duclouxii)、藏楸(Catalpa tibetica)、黄金树(Catalpa speciosa)、梓树(Catalpa ovata),其中黄金树是引入种,滇楸是灰楸的变型。从形态构造、亲缘关系和开花结果规律分析,可将5个种分为楸树组和梓树组2个组,楸树、灰楸和滇楸属于楸树组,藏楸、梓树和黄金树属于梓

Pollen Morphology of Several Species in Catalpa and Its Taxonomic Significance

Using scanning electron microscopy ( SEM ) ,pollen morphology of 23 individual plants from 5 species of Catalpa was observed. All of them were aggregated into tetrad with tetrahedron or crisscross or squareness or rhombus or erose arrangement. The tetrads were spherical or subspherical,and the diameter was from 29. 1 μm to 65. 1 μm. The tetrad was inaperturate,and the surface was bestrewed with colpates which were communicated with each other with anomalous directions. There was a reticulate pattern with various sizes and shapes of lumina that were sunken while the muri were protuberant. These species were differentiated mainly in the size and exine sculpture of the pollen tetrads. Catalpa speciosa had the largest pollen with 55. 8 μm in average,and Catalpa ovata had the smallest pollen with 42. 4 μm. Between the two there were Catalpa fargesii f. duclouxii,Catalpa fargesii,and Catalpa bungei with their pollen of 52. 9,47. 2,and 42. 7 μm,respectively. C. bungei and C. fargesii f. duclouxii had similar exine sculpture,while C. fargesii,C. ovata and C. speciosa shared similar exine sculpture. The pollen morphology is overlapped with each other between two groups of Catalpa,and it cannot be used for taxonomy,but there is taxonomic significance at species level within group. Special pollens with protuberance in colpus without reticulate sculpture were observed in C. bungei and C. fargesii f. duclouxii,however,was not observed in other three species.