Abstract
Seven plants species that belong to Asteraceae (Compositae) family have been investigated micro-morphology with the help of scanning electron microscopy (SEM) observations. Plants were collected from University of Baghdad campus during January to May in 2017-2018 and the species are: Calendula persica C. M. May, Carduus pycnocephalus L., Erigeron canadensis L., Lactuca serriola L., Silybum marianum (L.) Garth, Sonchus oleraceus L., Urospermum picroides (L.) Schmidt. The aim of this study was to describing the external morphology of seeds as well as a detailed study of pollen grains morphology. Special emphasis is given to the size, shape, polar and equatorial length, spines length, length and width of ora and colpi, tectum sclupturing, and the ornamentations on pollen surface, Sonchus oleraceus and Lactuca serriola pollen grains have a special exin sculpture, which is lophate and the other species used in this study is non-lophate, and all the pollen grains of the species used in this study are tri-zono- colporate, Calendula persica is only species that it is exin sculpture is echinate with spines length (3.8-4.3 um), and the exin sculpture of the other species is spinulose. Also special importance is given to the size, shape, pappus, beak length, primary and secondary sculpturing, carpopodium, as well as the surface of the seed (Cypsela), Seeds (cypsela) of the species used in this study were significantly different in morphology, The shapes of the 7 species were differed in each species and it showed 7 different shapes: narrowly-oblong, oblong, long-oblong, board-oblong, widely curved-oblong, narrowly-ellipitic, and narrowly-obovated.
Highlights
The plant kingdom include a large number of plant families that morphologically and anatomically difference, Asteraceae is the largest family in plant kingdom, The Asteraceae is one of the largest plant families (6, 25 and 32) reported, it has 1000 genera and about 23000 species
Spermoderm: The surface is rough, hairy, unwinged, with 10-11 ribbed faces, all the ribbed faces are joined at the base in a ring shape, the hair is only distributed at the top of the ribbed faces in different sizes and begin to fade into fine spines in the base of the cypsela, the hair is with pointed end, the surface between the ribbed faces is full with small spines, the secondary sculpture is papillose, carpopodium is present as a ring, beak width 0.2 um
The results lead to conclusion, where Calendula persica is only species that it is exin sculpture is echinate with spines length (3.8-4.3 um), and the rest species their exin sculpture is spinulose with spines length less than 3um, The character of pollen spine is significance in evolution and at specific and generic level in classification of this family (42). the measurements of spines differ from one species to the another, in which the longest spines (3.8-4.3um) is belong to Calendula persica, and other species that have length less (2 um) which are Erigeron canadensis, Carduus pycnocephalus, Lactuca serriola, Silybum marianum, Urospermum picroides, and Sonchus oleraceus spine length is (2.12.58 um), the shortest spine belongs to Lactuca serriola which is (1.0-1.4 um)
Summary
The plant kingdom include a large number of plant families that morphologically and anatomically difference, Asteraceae is the largest family in plant kingdom, The Asteraceae is one of the largest plant families (6 , 25 and 32) reported, it has 1000 genera and about 23000 species. RESULTS AND DISCUSSION Pollen grains According to Table 1 and 2, morphology of pollen grains of species used in this study is: Erigeron Canadensis According to the SEM images the pollen of Aster is monad, radically symmetrical, spheroidal in shape, Amb (peritreme), isopolar, Exin is spinulose, in polar view appear circular to sub-circular, the shape of pollen aperture is colporus ( with 3 colporus ), the grains are usually tri-zono-colporate , 3 coli that narrowed at the end and expand at the middle, the tectate is psilate , the length of the equatorial view (16.3-17.2 um), polar view ( 17.22-18.4 um ), coli length (8-10.9 um), coli width (1-1.5 um), ora length (5-6.6 um), ora width ( 5.2-6.8 um), mesocolpium width ( 11.4-12.3 um), apocolpium length ( 5.9-6.4 um),the spines are short, broad at the base, pointed and some of them curved, spine length (1.6-2 um), spine width (1.3-1.5 um) (plate.[1]). Spines , tectate of lophate is perforate, the 36.3-37.8 μm), coli length ( 34-34.5 μm), coli spines are short, board, pointed and some are width (0.9-1.4 μm), ora length (12 μm), ora curved, polar length( 30.3-31.4 μm), width (1.7-2 μm), spines length (1.4 μm), equatorial length (34 μm), ora length (6.3-7.4 spines width (1.9-2 μm) (plate.3)
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