Taxonomic studies on the grains of some wild and cultivated taxa of Poaceae

Abstract

The aim of this study was to produce a classification reflecting the relationships between the wild and cultivated species (taxa) of Poaceae by using the morphological features and Scanning Electron Microscope (SEM) characterizations of the grain surface of these species. To provide a background and to clarify the relationships among the studied taxa, the taxonomic histories of the family Poaceae (Gramineae) and genera were reviewed. The phenetic method of analysis (Single Linkage Clustering) were used to analyze the morphological features and surface scan of grain surface characteristics. Taxonomic relationships using the grains of 14 gramineous wild and cultivated species belong to 5 tribes and 6 genera of Poaceae were studied. Plants were Wild oat (Avena fatua L.), Common oat (Avena sativa L.), Animated oat (Avena steri/is L.), Sudan-grass (Sorghum x drummondii Nees ex Stendel), Sorghum (Sorghum virgatum (Hack.) Stapf., Rye-grass (Lo/ium multiflorum Lam.), Rye-grass (Lo/ium perenne L.), Boarded Rye-grass (Lolium temu/entum L.), Wild mill!(Echinochloa colona (L.) Link.), Barnyard-grass (Echinochloa crus­ galli (L.) P. Beauv.), Bristle-grass (Setaria pumila (Poiret) Roemer & Schultes),

Cannary-grass (Phalaris canariensis L.), Lesser cannary-grass (Pha/aris minor Retz.), Hood Cannary-grass or White-grass (Pha/aris paradoxa L.).

Taxonomic evidences for establishment the relationships among the above mentioned species included; 1) morphological descriptions of these species, 2) Scanning Electron Microscope survey on the grain surfaces of the studied species and 3) numerical analysis for the data obtained from 1 and 2. Morphological description results indicated that the two species; Sorghum x drummondii and Sorghum virgatum are more close to each other than to any of the other species and could be categorized to the tribe level. While the other twelve species ranked in a separate tribe levels. These species of the following of each genus are; Lolium (Lolium multiflorum, Lolium perenne and Lolium temu/entum); genus Phalaris (Pha/aris canadensis, Pha/aris minor and Phalaris paradoxa); genus Avena (Avena fatua, Avena sativa and Avena sterilis and the two of genus Echinochloa (Echinoch/oa colona and Echinochloa crus­ ga/11) in addition to genus Setaria (Setaria pumila). The scanning electron microscope on the grain surface and the numerical analysis results revealed that there eire eleven features of the grain surface could be recognized on the studied species. Through these studies, it was possible to trace the taxonomical relationships among the studied species through the morphological and scanning electron microscope of grain surface features. The proposed keys and classification to species are presented.