Number Of Ray Florets Research Articles

LECTOTYPIFICATION OF PECTIS L. (ASTERACEAE)

LECTOTYPIFICATION OF PECTIS L. (ASTERACEAE) David J. Keil' Linnaeus (1759a) described Pectis and included within it two species, P. ciliaris and P. linifolia. In 1913 Britton and Brown designated P. ciliaris as lectotype for Pectis. This lectotypification was accepted by editors of Index Nominum Genericorum (Plantarum) (Farr et al., 1979). I will present evidence below that lectotypification of Pectis by Britton and Brown was superfluous and that Pectis was actually lectotypified over 90 years earlier by Cassini. Britton and Brown as adherents of American Code of Botanical Nomenclature (Anonymous, 1907) followed mechanical practice of designating the first binomial species in order as lectotype of a genus. This appears to have been method of lectotypification used for Pectis. This practice is in conflict with provisions of Article 8 of International Code of Botanical Nomen- clature (Voss et al., 1983). The choice of Pectis ciliaris as lectotype is also in conflict with Linnaean protologue of Pectis. Linnaeus (1759a) included both a diagnosis (p. 1221) and a description (p. 1376) for Pectis. The diagnosis is very brief: PECTIS. Recept. nudum. Pappus aristatus. Cal. 5-phyllus, cylindricus. Flosculi radiantes 5. Of features described, receptacle, involucre [cal.] and number of ray florets are same for both P. ciliaris and P. linifolia. However, only P. linifolia has an aristate pappus. Linnaeus's description of genus is more thorough than diagnosis but he again described pappus of

ON THE VARIATION IN THE FLOWER HEADS OF ASTER TRIPOLIUM L. IN THE NETHERLANDS

SUMMARY In the Netherlands Aster tripolium L. exhibits a considerable variation in the number of ray florets per capitulum. There is a gradual transition from plants producing inflorescences with ray florets to plants producing exclusively flower heads without a single ray floret (so-called discoid plants). Discoid plants are particularly frequent in the south-western parts of the Netherlands, the populations occurring along the western Scheldt estuary (Westerschelde) showing the highest percentages of discoid specimens, but in the northern part of the country they are far less common. Discoid forms are chiefly found outside of the dikes. The number of ray florets per capitulum is not correlated with the number of disk florets. Accordingly, the recognition in the area of the Low Countries of varieties based on the number of ray florets does not seem to be recommendable.