Tribe Astereae Research Articles

CHROMOSOME NUMBERS IN COMPOSITAE VII: ASTEREAE III

Reports of 129 new chromosome counts are made for the tribe Astereae of Compositae. They are mostly based on determinations of meiotic material, including first counts for one genus and 43 species or subspecies. Counts are now available for more than 63 of the 100‐120 genera and 564 of the approximately 2,000 species in the tribe. Three of every four genera with more than one species counted show more than one chromosome number; 15 genera have species with populations with different numbers. Such variation is very high and indicates the need for more detailed cytotaxonomical study in the group.

Chromosome Numbers in Compositae VII: Astereae III

Reports of 129 new chromosome counts are made for the tribe Astereae of Compositae. They are mostly based on determinations of meiotic material, including first counts for one genus and 43 species or subspecies. Counts are now available for more than 63 of the 100-120 genera and 564 of the approximately 2,000 species in the tribe. Three of every four genera with more than one species counted show more than one chromosome number; 15 genera have species with populations with different numbers. Such variation is very high and indicates the need for more detailed cytotaxonomical study in the group.

Studies related to naturally occurring acetylene compounds. XXXV. Investigation of Erigeron spp. from the Australian mountains and Tasmania

Two Australian members of the genus Erigeron L. (Compositae, tribe Astereae) have been investigated with particular regard to their content of acetylenic compounds. E. conyzoides F. Muell. contained the methyl esters (I) and (II) of acetylenic carboxylic acids and their corresponding lactones (III) and (IV) and in this resemble the numerous Erigeron spp. of the northern hemisphere investigated earlier. Of the collective species E. pappochroma Labill. three Tasmanian and two Snowy Mountain collections were investigated. None of them contained the acetylenic compounds characteristic of typical Erigeron. Three of these collections contained some simple acetylenic alcohols, (V)-(IX); some of these are characteristic compounds of other genera of the tribus Astereae. In two collections acetylenic compounds were seemingly absent; but dill apiol (XI) was found in appreciable amounts.

CHROMOSOME NUMBERS IN COMPOSITAE V. ASTEREAE II.

Reports of 100 new chromosome counts are made for the tribe Astereae of Compositae, mostly based on determinations of meiotic material, including first counts for 9 genera and 53 species. Counts are now available for 58 of the approximately 100–120 genera and 431 of the approximately 2000 species in the tribe. Comparisons are made between chromosome number and habit and also between chromosome number and geographical distribution. Species and genera with a basic number of x = 9 are the most abundant. Within different phyletic lines x = 9 is also the most abundant number. On the other hand, many species with x = 4 and 5, belonging to a number of small, largely annual genera, are concentrated in southwestern North America. The low chromosome number in these plants is probably correlated with the dry habitat they occupy, and is most likely a specialized condition.

Chromosome Numbers in Compositae V. Astereae II.

Reports of 100 new chromosome counts are made for the tribe Astereae of Compositae, mostly based on determinations of meiotic material, including first counts for 9 genera and 53 species. Counts are now available for 58 of the approximately 100–120 genera and 431 of the approximately 2000 species in the tribe. Comparisons are made between chromosome number and habit and also between chromosome number and geographical distribution. Species and genera with a basic number of x = 9 are the most abundant. Within different phyletic lines x = 9 is also the most abundant number. On the other hand, many species with x = 4 and 5, belonging to a number of small, largely annual genera, are concentrated in southwestern North America. The low chromosome number in these plants is probably correlated with the dry habitat they occupy, and is most likely a specialized condition.

CHROMOSOME NUMBERS IN COMPOSITAE. I. ASTEREAE

Raven, Peter H. (U. California, Los Angeles.), Otto T. Solbrig, Donald W. Kyhos, and Richard Snow. Chromosome numbers in Compositae. I. Astereae. Amer. Jour. Bot. 47(2) : 124—132. Illus. 1960.–Ninety‐two new counts are reported for the tribe Astereae of Compositae, mostly based on determinations of meiotic material. These include the first counts reported for the genera Acamptopappus, Amphipappus, Benitoa, Chrysothamnus, Corethrogyne, Lessingia, Monoptilon, and Xanthocephalum, as well as for many species. The original counts are discussed in relation to those previously reported for the tribe; together these constitute a total of 39 genera examined cytologically out of the approximately 100 known. Because of its widespread occurrence in diverse phylogenetic lines within the tribe and the family, and because of its high degree of correlation with the woody habit, which is thought to be primitive, x=9 is regarded as the original basic number for Astereae. Within the Haplopappus alliance there is a strong secondary mode of chromosome numbers centering around x=5. The hiatus between these two modes in number is explained on the basis of ancient phylogenetic reduction in chromosome number followed by the extinction of less successful intermediate types, and is compared with similar trends that have been reported for Cichorieae. It is suggested that the family is not of polyploid origin but may have had an original diploid basic number.

Chromosome Numbers in Compositae. I. Astereae

Raven, Peter H. (U. California, Los Angeles.), Otto T. Solbrig, Donald W. Kyhos, and Richard Snow. Chromosome numbers in Compositae. I. Astereae. Amer. Jour. Bot. 47(2) : 124—132. Illus. 1960.–Ninety-two new counts are reported for the tribe Astereae of Compositae, mostly based on determinations of meiotic material. These include the first counts reported for the genera Acamptopappus, Amphipappus, Benitoa, Chrysothamnus, Corethrogyne, Lessingia, Monoptilon, and Xanthocephalum, as well as for many species. The original counts are discussed in relation to those previously reported for the tribe; together these constitute a total of 39 genera examined cytologically out of the approximately 100 known. Because of its widespread occurrence in diverse phylogenetic lines within the tribe and the family, and because of its high degree of correlation with the woody habit, which is thought to be primitive, x=9 is regarded as the original basic number for Astereae. Within the Haplopappus alliance there is a strong secondary mode of chromosome numbers centering around x=5. The hiatus between these two modes in number is explained on the basis of ancient phylogenetic reduction in chromosome number followed by the extinction of less successful intermediate types, and is compared with similar trends that have been reported for Cichorieae. It is suggested that the family is not of polyploid origin but may have had an original diploid basic number.

Astranthium and Related Genera

Monographic studies of Aphanostephus and Achaetogeron have made it necessary to investigate some of the related genera, particularly as to the value of certain morphological characters which are used in generic differentiation. The genera are quite similar in habit but the pappus, which furnishes important diagnostic characters, varies greatly within the group and is on the whole inconspicuous. For this reason it is necessary to make microscopic studies of the minute achenial and pappus characters upon which the differentiation of genera is primarily dependent. In this connection it was desirable to study Astranthium and Keerlia in detail; and it seems advisable to put on record the results which have been obtained relative to these genera. Astranthium, a genus of the Compositae belonging to the tribe Astereae, was described by Nuttall in 1841.1 It contained but one species, A. integrifolium, based on Bellis integrifolia Michaux.2 The 'Flora of North America,' published by Torrey and Gray in 1842, relegated Astranthium to synonymy. Since that time American and Mexican species have been merged with the genus Bellis3 which is indigenous to the Old World and especially to Europe. Three South American species have been described by Vellozo4 as occurring in Brazil. Two of these, Bellis campestris Vell. and B. pedunculata Vell., may well be members of the genus Spilanthes. The relationship of the third, Bellis scandens Vell., is unknown to me. Bellis perennis L. is an attractive plant, and for this reason it has been cultivated in the north Atlantic states where it has become naturalized. The American species which have been referred hitherto to the genus Bellis are so strikingly different that it seems strange the two generic elements should have been regarded