PLANT MACROFOSSIL METHODS AND STUDIES | Treeline Studies

Macrofossil series from mountainous and polar areas such as the Alps, the Scandes, and the Rocky Mountains provide useful information about the late Quaternary course of treelines. Reconstructions of past treeline positions and compositions after the Ice Age can be used to infer paleoclimatic information or to study treeline ecosystem responses to (rapid) climatic change. Both approaches are illustrated by study cases. In addition to these paleoclimatic and paleoecological issues, macrofossil records can be used to validate dynamic treeline vegetation models. An example from the Alps shows the high potential of such a procedure towards applying forest-succession models for assessing future vegetation dynamics at treeline.

Patterns of Stem Cell Divisions Contribute to Plant Longevity

The lifespan of plants ranges from a few weeks in annuals to thousands of years in trees. It is hard to explain such extreme longevity considering that DNA replication errors inevitably cause mutations. Without purging through meiotic recombination, the accumulation of somatic mutations will eventually result in mutational meltdown, a phenomenon known as Muller’s ratchet. Nevertheless, the lifespan of trees is limited more often by incidental disease or structural damage than by genetic aging. The key determinants of tree architecture are the axillary meristems, which form in the axils of leaves and grow out to form branches. The number of branches is low in annual plants, but in perennial plants iterative branching can result in thousands of terminal branches. Here, we use stem cell ablation and quantitative cell-lineage analysis to show that axillary meristems are set aside early, analogous to the metazoan germline. While neighboring cells divide vigorously, axillary meristem precursors maintain a quiescent state, with only 7–9 cell divisions occurring between the apical and axillary meristem. During iterative branching, the number of branches increases exponentially, while the number of cell divisions increases linearly. Moreover, computational modeling shows that stem cell arrangement and positioning of axillary meristems distribute somatic mutations around the main shoot, preventing their fixation and maximizing genetic heterogeneity. These features slow down Muller’s ratchet and thereby extend lifespan.

Radioisotopes in agriculture : animal husbandry, fertilizer uptake, plant physiology, photosynthesis, and entomology : a selected list of references /

This bibliography contains 151 selected references on the uses of radioactive and stable isotopes in animal husbandry and in studies of fertilizer uptake by plants, plant physiology, photosynthesis, and entomology. These references were selected from scientific journals published during the period 1957-1958. An author index is included.

Ernest H. Wilson, plant hunter.

Mode of access: Internet.

Laboratory manual for plant biology,

Lithoprinted from type-written copy, with printed t.-p.

Winter botany ...

A companion volume to the author's Plant materials of decorative gardening.

An introduction to structural botany : part II, flowerless plants /

Includes index.

Radioisotopes in agriculture : animal husbandry, fertilizer uptake, plant physiology, photosynthesis, and entomology : a selected bibliography /

This annotated bibliography contains 148 selected references on the uses of radioactive and stable isotopes in animal husbandry and in studies of fertilizer uptake by plants, plant physiology, photosynthesis, and entomology. These references were selected from scientific journals published during the period 1957-1958. Subject and author indexes and a list of the periodicals from which the references were selected are included.

Botany current literature.

Botany current literature.

Caspari Commelin ... Horti Medici Amstelædamensis plantæ rariores et exoticæ ad vivum æri incisæ

Mode of access: Internet.

Manuale botanicum peregrinationibus botanicis accomodatum : sive Prodromus enumerationis plant. phaenogam, in Germania sponte nascentium /

Mode of access: Internet.

Plants; a text-book of botany.

Includes indexes.

Ecoclass coding system for Pacific Northwest plant associations /

Mode of access: Internet.

Glimpses at the plant world,

Mode of access: Internet.

Contributions to geology and plant physiology.

Mode of access: Internet.