Secondo Contributo Alla Conoscenza Dello Sviluppo Embriologico del Genere Centaurea L. (Asteraceae). Centaurea Horrida Bad

Summary

The Author has studied the embryological development of Centaurea horrida Bad., pure pliocenic endemisms of Sardinia and has established that:

1°) the cromosomic number of the species is: 2n = 18.

2°) the genesis of microspores is of simultaneous type;

3°) The archesporium is constituted of one cell only seldom accompanied by a basal cell;

4°) the development of the female gamethophyte is of normal type;

5°) even showing cases of degenerated antipodal cells, the species has a marked tendency to the polyantipody, sometimes also characterized by a strong hypertrophy of its cells;

6°) in the species the contemporary germination of some megaspores in the same ovule is enough frequent;

7°) there are also some cases of coesistence of some gamethophytes in their different stages of development;

8°) the phenomenon of «multiple oospheres» and of «multiple synergidae» may happen;

9°) in some ovules, near the egg-apparatus, cells of two or four nuclei may be found.

For these last ascertainments (8° and 9°) the Author makes the hypothesis that it may be probably an anomalous prolification of micropylar nuclei, or asynchronous development, for delayed germination of some micropylar megaspores producing primary stages of gamethophyte.

Moreover the Author has the opportunity to bring into evidence:

10°) a case of ovular teratology represented by the extraovular development of an adult gamethophyte very similar to those previously found by the Author himself in Petasites fragrans;

11°) frequent cases of regretion of female sexuality, founding that about the 10% of the flowers examined were functionally male. The Author has fronted the possibility of the existence, in Asteraceae, also of the type of inflorescence where «flowers are all tubulated: the marginal ones neuter, the others or hermaphrodite or hermaphrodite and male».     

Morfologia di Neobarclaya Natalensis Syd.

Summary

The morphology of Neobarclaya natalensis Syd., parasite on the leaves of Syzigium guineense DC., is described. Some characters are esp. stressed, such as the shape of the acervula, their position within the host tissues, some morphological peculiarities of the conidia, the nature and localization of their pigment.

Considerations on the systematic position of the fungus are exposed and the original diagnosis of J. B. Ellis and B. M. Everhart is enlarged and emendated.

Some morphological relations between the fungus under examination and the genera, esp. Melanconiales, showing dark, pluriseptate, appendaged conidia, are discussed.

Systematical and morphological considerations are then reported on the other two species of the genus Neobarclaya Sacc.: N. primaria (Ell. and Ev.) Sacc. and N. flagellifera (Ell. and Ev.) Sacc., the first of which is to be considered as the type species of the genus and the second one, due to its single apical seta, is segregated from Neobarclaya as the type species of a new genus of Melanconiales: Uniseta, which is different from Neobarclaya because of the above mentioned character, from Monochaetia Sacc. because of its 2-cellular conidia and from Monotrichum Gaüm. because of the dark pigment present in its conidia.     

Centaurea carpatica

Ohne Zusammenfassung     

Sesquiterpene lactones from Centaurea thessala and Centaurea attica. Antifungal activity

The aerial parts of Centaurea thessala ssp. drakiensis and C. attica ssp. attica afforded, in addition to several known sesquiterpene lactones, two new eudesmanolides, 4-epi-sonchucarpolide and its 8-(3-hydroxy-4-acetoxy-2-methylene-butanoyloxy) derivative and one new eudesmane derivative, named atticin. The in vitro antifungal activity of most compounds was tested against nine fungal species, using the micro-dilution method. All the compounds tested showed great antifungal activity.     

Elemanolides from Centaurea melitensis

Two new elemanolides isolated from Centaurea melitensis L. have been shown to correspond to the β-hydroxyisobutyrates of melitensin (1c) and its 11(13)-dehydro derivative (1a).     

Guaianolides from Centaurea kotschyi

The aerial parts of Centaurea kotschyi (var. kotschyi) afforded, besides three known sesquiterpene lactones, a new derivative of linichlorin B.     

Sesquiterpenes from Centaurea aspera

The aerial parts of two subspecies of Centaurea aspera L. (Asteraceae) yielded the germacranolides 1a-h, 2, 3, 4 and 5, the elemane derivatives 6d and 6f, the lignan matairesinol, the degraded terpene loliolide, and the onopordopicrin-valine dimeric adduct 7. From these, compounds 1e, 3 and 6d are natural products. The chemical composition of the two subspecies is very similar, a circumstance which does not support a taxonomic subdivision of the species.     

Guaianolides from Centaurea canariensis

The reinvestigation of Centaurea canariensis var. subexpinnata provided, along with three known compounds, three new sesquiterpene lactones of the guaiane series.     

Composition and antimicrobial activity of essential oils from Centaurea sessilis and Centaurea armena

The essential oils of air-dried Centaurea sessilis and Centaurea armena obtained by hydrodistillation were analyzed by gas chromatography-mass spectrometry (GC-MS). Forty and twenty components were identified in the essential oils and the main component of these taxons was beta-eudesmol in the ratios of 12.4% and 19.3% from C. sessilis and C. armena, respectively. The antimicrobial activity of the isolated essential oil of the plants was also investigated. They showed moderate antibacterial activity against Gram-positive and Gram-negative bacteria, but no antifungal activity was observed against two yeastlike fungi.     

Chlorohyssopifolin C,D, E and vahlenin,four new sesquiterpene lactones from Centaurea hyssopifolia

On the basis of chemical and spectroscopic evidence, structures are assigned to four new sesquiterpene lactones: chlorohyssopifolin C, D and E (guaiano     

Weitere acetylenverbindungen aus Centaurea ruthenica

Reinvestigation of the polar fractions of the aerial parts of Centaurea ruthenica afforded, in addition to known compounds, more than 20 new ones, mostly in very small quantities, which in many cases could only partly be separated even after acetylation. The structures, however, could be elucidated by spectroscopic methods. Besides additional C₁₃-acetylenes, several new C₁₄- and C₁₀-acetylenes are present. The compounds isolated are of special interest in view of the proposed biosynthetic scheme of acetylenic compounds of this type.     

Polyunsaturated compounds of Centaurea scabiosa

Roots, green parts, and flower heads of Centaurea scabiosa were examined separately. Twenty-five polyacetylenes, 4 polyenic aldehydes, 1,8,11,14-heptadecatetraene, and the flavone apigenin were isolated and characterized. Three C₁₇ hydrocarbons with from one to three isolated double bonds and a series of minor compounds were also isolated.     

Il sospensore embrionale nelle Cruciferae. I. Morfologia e struttura

Abstract

Embryo suspensor in Cruciferae. I. Morphology and structure. — Embryo suspensors in seven species of Cruciferae (Alyssum argenteum All., Brassica nigra (L.) Koch, Capsella bursa-pastoris (L.) Medicus, Diplotaxis erucoides (L.) DC., Eruca sativa Miller, Lepidium graminifolium L., Matthiola tricuspidata (L.) R. Br.) were morphologically investigated. These species have significant differences in their seeds, so that probable differences could be found in the structure of their ovules and therefore of their suspensors. Results indicate that it is impossible to generalize on the suspensor morphology and structure even in the same family. In Eruca sativa and Brassica nigra polyploidy and polyteny were found, suggesting a probably important metabolic function of their suspensors. In the other species polyteny was not present; a various degree of polyploidy could probably be assumed, suggesting a less active function of suspensors, maybe absorption and transport of nutritive material from the integuments to the developing embryo. The development of the endosperm is almost the same in all species, so that seems to be improbable a negative correlation with the suspensor and endosperm function in the early embryogenesis.