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Karyological and chemical variations in Allium sativum L. — Results about a research on the karyotypes of three Italian strains of Allium sativum are reported. The lack of sexual reproduction in Allium sativum favours the formation of strains regarded as clones; each of them represents an isolated genetic system. The anatomy and the chemical composition of the essence was studied to improve the understanding of the variations in the different strains comprised in this species. Two of the clones examined (Tuscan and Sicilian) belong to U type and one (Piedmontese) to the H type, according to Hrubý and Konvicka's classification based on the morpho-physiological characters. In this study evidence shows that: a) The three clones do not present anatomical differences. b) The morpho-physiological characters are strictly correlated with the chemical composition of the essence; in fact the gas-chromatographic study of the two U type clone essences shows the same qualitative composition, each chemical com...

ARTEMISIA CAERULESCENS L. var CRETACEA Fiori: its morphology, anatomy and santonin content. — Artemisia caerulescens L. var. cretacea Fiori, endemic of the loamy soils of Romagna and Tuscany, has been collected near Siena and specimens have been submitted to morphological, anatomical, systematic researchs. The names of previous botanists who have collected this plant in the surroundings of Siena have been listed. The big underground apparatus of Artemisia and the variable morphological characters of the species, expecially for the inflorescence, have been put in evidence. The most outstanding anatomical characters of var. cretacea are the following: 1) in the overground stem (that means in the inflorescence axis) glandular hairs and T hairs are present, persisting also when the cork tissue is formed; the collateral vascular bundles are surrounded by a sclerenchymatic cap, outside the phloem; the parenchyma cells of the protoxylem area in the primary and secondary structure are not lignified; some...

The embryological development of Erigeron speciosus DC. — The Author refers on the embryology of Erigeron speciosus DC. listing the most important characteristics of the development of this gametophyte a) a pluricellular archesporium is formed, with fertile and sterile cells. b) several mother cells develop inside a single nucellus leading to the formation more than one gametophyte; c) at the end of the meiotic process different conditions may be reached; that is: tetramegasporial apocitium; II) trimegasporial apocitium plus a megaspore; III) dimesporial apocitium plus two megaspores at the two ends of the apocitium; d) the gametophyte may vacuolate with different patterns. e) different types of development may occur in the gametophyte, that is: I) from tetrasporic cell of a 16-nucleate gametophyte with a monosporial oangium; II) from trisporic cell of a 12-nucleate gametophyte with a monosporial oangium; III) from disporic cell of a 8-nucleate gametophyte with a monosporial oangium. f) Erigeron ...