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Results tagged “march-05”

Mar 5, 2014: Pinus sylvestris

Pinus sylvestris

Taisha is the author of this entry. She writes:

Today, we have a photo of Pinus sylvestris, commonly known as Scots pine, showing the needles and male cones (microstrobili). The image is courtesy of Marianne (aka marcella 2/tovje@Flickr, and was shared via the Botany Photo of the Day Flickr Pool. The Flickr pool has another image of the species in habit by Stephen Buchan (aka --Green Light Images--@Flickr). Thank you both for sharing!

Pinus sylvestris is the second-most widely distributed conifer in the world (exceeded only by Juniperus communis), with a native range spanning beyond the Arctic Circle to southern Spain, and from western Scotland to eastern Siberia. The species grows at elevations from sea level to 2400 meters (~8000 ft.).

The last major episode of widespread glaciation, about 10 000 years before present, occurred during the Pleistocene. During this time, many plant species survived in small isolated ice-free areas known as glacial refugia. For Scots pine, evidence so far suggests the species survived in four main refugia as well as an area south of glacial extent (the Russian Plains). The four refugia were: 1) the Iberian Peninsula, 2) the northern Apennine Peninsula, 3) south of the Carpathian and Sudeten Mountains, and 4) the Balkans. As the glaciers retreated, Pinus sylvestris recolonized Europe. However, it is still unclear which routes and specific refugial populations had the most prominent roles.

In a study by Prus-Glowacki, et al., some suggestions about the recolonization patterns of the Scots pine after the last glaciation are made. They propose that the Iberian and Apennine Peninsulas populations either did not at all, or only slightly contributed to recolonization. Furthermore, they state that the Balkan refugium contributed as a source area for Scots pine migration into central and western Europe, while those ancestral populations from eastern Europe and Siberia primarily contributed to the present gene pools in central Europe and Scotland. Lastly, the researchers note that the origin of the Scottish populations is unclear, as they form a distinctly separate group derived from more than one glacial refugium after the last glaciation (see: Prus-Glowacki, et al. (2012). Genetic variation of isolated and peripheral populations of Pinus sylvestris (L.) from glacial refugia. Flora-- Morphology, Distribution, Functional Ecology of Plants. 207(2):150-158).

In a previous BPotD entry from 2011 about Loch Maree, Scotland, Daniel mentions Pinus sylvestris and briefly touches on the biogeography of this species, with particular attention to its presence in the Loch Maree area.

Mar 5, 2013: Rhododendron mucronulatum

Rhododendron mucronulatum

This photograph was taken yesterday in UBC Botanical Garden's Winter Garden. I visited the site to observe the progress on the accessibility pathways being developed in partnership with the Garden's new neighbour, the still-under-construction St. John Hospice.

Rhododendron mucronulatum, or Korean rhododendron, is native to China, Japan, Korea, China and Mongolia, where it is frequently found inhabiting birch (Betula) and larch (Larix) forests and forest margins. These deciduous shrubs (maximum height about 2.5m (8 ft.) are one of the earliest-flowering Rhododendron species in UBC Botanical Garden. Our plants have a particular airiness about them, which I tried to capture in the image; however, some other online images show plants with a higher density of inflorescences and shorter branch internodes (i.e., less "twiggy"), e.g., Rhododendron mucronulatum 'Deep Pink' via the Missouri Botanical Garden. Additional photographs can be found via the virtual arboretum hirsutum.info: Rhododendron mucronulatum.

Photography resource link: the photography of Barney Wilczak. Be sure to browse the galleries!

Mar 5, 2012: Chlamydomonas reinhardtii

Chlamydomonas reinhardtii

Katherine has been busy assembling this year's UBC Celebrate Research Week series, starting with today's entry:

Dr. Jae-Hyeok Lee is an Assistant Professor with the UBC Department of Botany. He describes the research currently being undertaken by the Lee Lab as work in the hope of "understanding the ancestral conditions prior to the origin(s) of plant development".

Dr. Lee continues: In order to do this, the lab studies cellular mechanisms that orchestrate zygote development in Chlamydomonas, a green alga genus. Systematic approaches, including molecular genetics, comparative genomics and live cell imaging, have so far yielded a grand hypothesis that the green algal zygote is functionally and evolutionarily related to the plant sporophyte where most plant-specific structures such as leaf, seed, and flower have evolved. We believe that deeper understanding of green algal zygotes will guide us to follow individual evolutionary steps in the preceding billions of years from unicellular green algae to flowering plants.

The picture above was taken by a phase-contrast microscope and captures the most exciting and fierce moment of a green alga, Chlamydomonas reinhardtii during its sexual mating. Oval shaped, and averaging 5 micrometers in length, a Chlamydomonas cell (in the lower right corner) is a very good swimmer, utilizing two flagella on its apical side to move as it looks for either sunlight or a mating partner. Nutrient starvation induces cells to become gametes that participate in mating reaction. They are either of two sexual types, plus or minus, each reacting to its opposite sex as their flagella adhere only to the flagella of the other sex (red arrow). Upon flagellar adhesion, two gametes shed their cell walls (yellow arrow) and proceed through a cellular fusion process which takes only a couple of minutes (blue arrow). The union of cells initiates dramatic restructuring to differentiate as a dormant zygote that can endures a cold and dry winter.


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