#hemiparasite

Image Source: https://www.inaturalist.org/taxa/57512-Viscum-album

PLANT OF THE WEEK – Viscum album (common name: Mistletoe, mistelten). Mistletoe is particularly eye-catching during wintertime as lush, green globes high in the leafless treetops. Its many small, pearly white berries form a striking contrast to its evergreen foliage. Mistletoe is an evergreen hemiparasite with branches more than 50 cm long. The shoot system is dichotomous with opposite, ligulate leaves. There are female and male plants. The 1-3 mm long yellow-greenish flowers are placed apically in groups of three. In male flowers, the anthers are fused with perianth segments. Female flowers have an inferior ovary with a sessile stigma. They are pollinated in April, mainly by small flies. The fruit is a white berry with a very sticky pulp. All parts of the plant are moderately poisonous. The berries develop in autumn and winter and provide food for migrating birds, mainly Bohemian waxwings and mistle thrushes. The berries quickly pass through the bird, and the defecated seeds can be seen dangling from branches in sticky garlands strung together by undigested remnants of the pulp. The Eurasian blackcap uses its beak to squeeze the seed from the fruit before it is eaten. To remove the sticky seed, the bird rubs its beak against a twig, thus depositing the seed in a place it is likely able to germinate. Mistletoe grows on many species of deciduous trees (some on conifers). It attaches to its host by a haustorium, a modified root, which penetrates the vessels, from where it obtains water and nutrients. The mistletoe has chloroplasts and can perform photosynthesis; hence the term ‘hemiparasite’. Interestingly, the mitochondrial genome of mistletoe is much smaller than that of other plants and lacks many important genes, causing inefficient energy production. The mistletoe can cope on this low energy budget due to its very slow growth and parasitic lifestyle. Today, mistletoe is widely distributed in Europe south of Denmark. Fossil records from 9,000 – 6,000 years ago show that mistletoe has previously been present in Denmark. After being extinct for many years, introduced specimens from gardens are now spreading in Denmark, especially around Copenhagen. Throughout history, mistletoe has played a role in many cultures. It was believed to possess magical powers, e.g. by the Celtic druids. In Denmark, we know the mistletoe from Nordic mythology, where the goddess Frigg forgot to extract an oath from the deceptively innocuous mistletoe, when she made all beings swear to never harm Balder. Today, it is mainly associated with the Christmastime custom that whoever stands beneath a mistletoe may be kissed. Though mistletoe has long been regarded as a fertility symbol, this custom is fairly new as it is first described in England in the mid-18th century. This Plant of the Week is presented by Niels Jacobsen, Kira Tendal, Karen Rysbjerg Jensen and marian ørgaard, employees at the Department of Plant and Environmental Sciences, University of Copenhagen.

bonus: cute little bold jumper lurking hard. 

Indian paintbrush (Castilleja) is a hemiparasite-a plant that obtains some or most food by parasitism but still photosynthesises. This one seems to be feeding on ceanothus

First time finding #PedicularisDensiflora/#WarriorsPlume and I almost didn’t! It’s a hemiparasitic plant, as you may have guessed from the color. #orobanchaceae #parasiticplant #hemiparasite #pedicularis #californianativeplants #californianativewildflowers #canativeplants #otaymountain #botany (at Otay Mountain Wilderness Area) https://www.instagram.com/p/CMAINZaDUhL/?igshid=87oswsgh6g4u

Hemiparasitic on oaks, which is neat.

http://www.jstor.org/stable/10.1086/303294

Meet Euphrasia nemorosa, the eyebright. This lovely little plant is native to the northern regions of North America. A quick glance at the flowers of this species may seem to suggest a member of the mint family but this would be wrong. Once placed in Scrophulariaceae, it is now thought to reside in Orobanchaceae. Like other members of this group, E. nemorosa is a hemiparasite. It uses specialized roots to tap into the roots of plants growing around it. In the wild, research has shown that E. nemorosa seems to prefer to parasitize grasses but laboratory experiments have shown that it will parasitize a variety of plants if given the chance. It can even grow without parasitizing other plants but those that did grew small and weak.  Parasitic plants are an interesting bunch. They push the limits of what is traditionally accepted in the realm of plant physiology. Non-parasitic plants usually have to balance between CO2 uptake and water loss. They do this by controlling their stomata, which are tiny openings on the leaf. Because they are attached to a host, parasitic plants do not have to worry about minimizing water loss and instead want to maximize water loss to gain as much carbon from their host plant as possible.  Another interesting aspect of Euphrasia ecology is their preference for disturbance. Euphrasia are plants of disturbed meadows, fields, and man-made habitats. There is a lot of work being done to examine which kinds of species thrive in and around humans. Research has shown that by selecting for native species like Euphrasia, the species composition on these types of disturbed habitats can take on a more biodiverse character instead of the usual non-native monoculture. Further Reading: https://gobotany.newenglandwild.org/species/euphrasia/nemorosa/ http://www.archive.bsbi.org.uk/Wats6p1.pdf http://jxb.oxfordjournals.org/content/39/8/1009.short http://www.archive.bsbi.org.uk/Wats5p11.pdf