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Coihimtia isowv of llic largest ^t'lit'ia of \\\c Irilx' Mutisieae (Aslcraceac) ami has IxM'ri Iradilionally charactrri/rd by its honio^anious rupitula wilh isoinuqiliu-toiollas. A itKuplioloi^ical sluil} o[ GocluKtlid and associated ^t'lu'ia. i.e., Arfinosrris, Chnvoa, (Inicothdiunus, ('yrlolcpis, Uyalis, lauthopappiis, Nonelia, Plciotaxis, and Wundvrluhia, was canlcd out lo rvalna!<' \\\v circiiinscriplion (»f (Unhnutid and ils sections, and the affitiilirs of this complex of genera. The characters studied involve hahil, U^af features (consistency, |>ul)escence lyj>e, shape, margin, and venation), types of capiluiescence, inxolu

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Environmental gradients are caused by gradual changes in abiotic factors, which affect species abundances and distributions, and are important for the spatial distribution of biodiversity. One prominent environmental gradient is the altitude gradient. Understanding ecological processes associated with altitude gradients may help us to understand the possible effects climate change could have on species communities. We quantified vegetation cover, species richness, species evenness, beta diversity, and spatial patterns of community structure of vascular plants along altitude gradients in a subarctic mountain tundra in northern Sweden. Vascular plant cover and plant species richness showed unimodal relationships with altitude. However, species evenness did not change with altitude, suggesting that no individual species became dominant when species richness declined. Beta diversity also showed a unimodal relationship with altitude, but only for an intermediate spatial scale of 1 km. A lack of relationships with altitude for either patch or landscape scales suggests that any altitude effects on plant spatial heterogeneity occurred on scales larger than individual patches but were not effective across the whole landscape. We observed both nested and modular patterns of community structures, but only the modular patterns corresponded with altitude. Our observations point to biotic regulations of plant communities at high altitudes, but we found both scale dependencies and inconsistent magnitude of the effects of altitude on different diversity components. We urge for further studies evaluating how different factors influence plant communities in high altitude and high latitude environments, as well as studies identifying scale and context dependencies in any such influences.

FREIRE, S. E., CRISCI, J. V. & KATINAS, L., 1993. A cladistic analysis of Nassauvia Comm. ex Juss. (Asteraceae, Mutisieae) and related genera.Nassauvia and the most closely related genera Calopappus and Triptilion from the southern Andes and Patagonia of South America, form a monophyletic group diagnosed by the following synapomorphies: cypsela trichomes single two‐celled, cypsela testa with strengthened cells, pollen grains spheroidal to spheroidal‐oblate, colpi membrane with sexine processes, pappus bristles two to six, and pappus deciduous. Furthermore, Nassauvia, Triptilion, and Calopappus form a group with two other Andean genera, Moscharia and Polyachyrus, diagnosed by occurrence of pseudocephalia and a reduction in the number of flowers to five, three or one. A cladistic analysis of the group was undertaken using 35 characters from morphology, anatomy, and palynology. The monophyletic terminal taxa were the 38 species of Nassauvia, the genus Triptilion, the monotypic genus Calopappus, the genus Polyachyrus, and the genus Moscharia. Character polarity was based on outgroup comparison using Cephalopappus. The analysis resulted in 223 equally parsimonious cladograms, each with 70 steps and a consistency index of 0.57. A successive weighting procedure was applied, resulting in 15 cladograms with a consistency index of 0.82. Results of the cladistic analysis support most of the current systematic classification of Nassauvia, with three exceptions: (1) Nassauvia (excluding Calopappus) is paraphyletic; (2) section Masligophorus appears to be a polyphyletic group (N. pygmaea does not cluster with the remaining species of the section); (3) section Panargyrum (without N. lagascae= section Caloptilium) appears to be a paraphyletic group. The capitula arranged in cymose conflorescences in Triptilion are regarded as a primitive condition which gave rise to all stages present in Nassauvia (conflorescence spicate, pseudocephalium, capitula solitary). The capitula arranged in pseudocephalia in Moscharia and Polyachyrus are regarded as a parallel development to the pseudocephalium found in Nassauvia. Nassauvia, subgenus Strongyloma appears as the most primitive taxon, with its spicate conflorescence, whereas section Masligophorus with its solitary capitulum is thought‐derived. These results correspond well with cytological data where species of the subgenus Strongyloma have n= 11 and the species of section Masligophorus are tetraploids (n = 22).

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Based on a detailed study of morphology and a critical analysis of species limits, we present a synopsis of Senecio ser. Culcitium from Andean South America. In this synopsis, Senecio ser. Culcitium is circumscribed including Aetheolaena and Lasiocephalus, two genera which are nested within Senecio. Forty three species are recognized in S. ser. Culcitium that are either rosette or scapiform herbs or subshrubs (sometimes scandent) bearing usually entire leaves, discoid and nodding capitula usually with conspicuous calycular bracts, penicillate style arms with or without a tuft of long hairs, and microechinate pollen. The new combination Senecio hyoseridis is proposed. The following names are proposed as synonyms: Senecio comosus var. debilis and S. comosus var. blancus with S. comosus; Senecio cuencanus var. tomentella with S. cuencanus; Senecio decolor, S. iscoensis and S. rosanus with Senecio antisanae, Senecio eliseae with S. rhizomatus; Senecio hypsobates var. parvulus with S. hypsobates; Senecio mochensis with S. pindilicensis; Senecio modestus with S. candollei; Senecio neeanus and S. haenkeanus with S. nivalis; Senecio quitensis with S. superandinus; Senecio santanderensis with S. cocuyanus; Senecio yacuanquensis with S. otophorus; Senecio zoellneri with S. keshua. Ten species previously placed in Senecio ser. Culcitium, i.e., S. aspleniifolius, S. candidans, S. comosus, S. diemii, S. gilliesii, S. jarae, S. julianus, S. magellanicus S. martinensis and S. stylotrichus, are excluded. Two of them, Senecio gilliesii and S. candidans are placed within Senecio ser. Hualtatini mainly by their herbaceous habit, stems usually leafy up to the apex, and erect capitula. Senecio jarae and S. aspleniifolius are placed in a new series based on the previously described Senecio sect. Repentes because of their solitary erect capitula and entire or deeply lobed leaves. Lectotypes are designated for 13 names. Additionally, 11 new illustrations, distribution maps, and identification keys are presented.

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