Friday, June 12, 2015

Plants considered parasitic actually have positive impacts on greater increases in biodiversity

Okay, so the original title of the University of York's research study wasn't exactly so flowery. The original title was: " ‘Vampire’ plants can have positive impacts up the food chain. " Okay so I dislike terms like ‘Vampire’, ‘Devil’, ‘Hell’, etc being applied to kool things in Nature. I predict one day mankind globally will rename many natural wonders which have been shackled to derogatory descriptions because of certain perceived spooky characteristics. Hopefully this will be happening sooner than we all think.

Rhinanthus, Castle Hill National Nature Reserve in Sussex
"New research has revealed that parasitic 'vampire' plants that attach onto and derive nutrients from another living plant could benefit the abundance and diversity of surrounding vegetation and animal life."
(Source - University of York)

The Plant celebrity in the published article from the University of York in Great Britain is an annual root-hemiparasite of nutrient-poor grasslands called Rhinanthus minor or commonly known as Yellow Rattle. It is also found in permanent pastures, hay meadows, the drier parts of fens, flushes in lowland and upland grasslands, and on montane ledges; also on roadsides and waste ground. It's classified as what is known as a hemi-parasitic which means it draws nutrition from it's host, but also from Chlorophyll, just like other familiar better known hemi-parasitic plants who also have a host and draw nutrition from the sun through photosynthesis, the common Mistletoe. Life benefits from such associations which in our modern times have been discovered with Mistletoe and trees or shrubs. So too has great importance been discovered with the presence of Yellow Rattle (Rhinanthus minor) to the biodiversity of fields and meadows in not only holding back more aggressive plants which would proliferate in the absence of Yellow Rattle, but also the unexpected abundance of biodiverse populations of all manner of insects, [butterflies, snails, wasps, etc] animals and birds. 

"Lead author, Professor Sue Hartley, of the Department of Biology at York and Director of the York Environmental Sustainability Institute, said “This was a really unexpected finding. Although hemi-parasites are known to increase the diversity of other plants in the community by suppressing the dominant species they parasitize and so allowing other plants to flourish, none of us predicted there would be such dramatic and positive impacts on other components of the grassland community."
“Rhinanthus minor (Yellow Rattle) increased the abundance of all sorts of animals including snails, woodlice, butterflies, wasps and spiders. This is an important finding for the conservation and management of these chalk grassland communities, which are exceptionally species rich but also rare and threatened.”
(Source: University of York)
Interestingly, many cattle ranchers and farmers with various grazing animals period generally are looking for a monoculture in fields and meadows where they place their animals. They want grasses and nothing more. But monoculture seems to be the desired human pursuit these days, especially with regards industrial agriculture backed by horrible science which discounts the benefits of biodiversity. They are ignorant of the fact that many of these other Forbes [noxious weeds in their warped opinion] have health benefits to their livestock. Great article about field biodiversity and it's importance, but again as a recap, not only do these and other plants suppress  certain aggressive plants which would  overwhelm the ecosystem with populations of dense grasses, but it opens the field up to other lifeforms which are important to ecosystem health overall.
"The changes induced in the plant community were consistent with previous studies of the impact of  'Yellow Rattle' - Rhinanthus minor, particularly in the suppression of grasses. However, the striking enhancement of invertebrate abundance across several trophic levels has not been recorded previously."
Hemiparasitic Plants of the Western United States
Image: Sprouts Greenhouse, Landers Wyoming

Indian Paintbrush Integra
(Castilleja integra/
Artemesia frigida)

Indian Paintbrush (Castilleja integra)
This got me thinking of a couple of native wildflowers where I originally come from in the Western USA. Ones I am most familiar with, but also ones I come to find I should know more about. I never paid much attention to wildflowers of SoCal before other than common & Scientific names. My thing has always been chaparral and trees native to the same region. And of course the community relationship between them as an active functioning living biological machine. However, it seems like the more I discover, the more I really don't know. Human lifespans for the present just aren't long enough to find out all there is to know and benefit from. But I now wonder about such plant's roles and purpose within the ecosystems I am familiar with in SoCal. For example, when I lived in Anza California previously for over 20+ years, I was most familiar with the Indian Paintbrush  wildflower. What was interesting was that this plant was always mostly found in association with a chaparral plant called Silver Sagebrush like the one you see above in the larger photo. Now while I always knew it was partial parasitic, I knew it never harmed the Sagebrush as most people would normally have a view of things we label as parasites. Now with further information from the University of York, I am further curious as to ecosystem roles of this plant. Providing pollination for various bees, wasps and other winged insects, what else does it accomplish ? Does it keep the Silver Sagebrush (Artemesia) in check or balanced and where it's not overwhelming the entire system ? Do other things like birds or animals benefit from it's presence in the system ? Questions, Questions, Questions and more Questions.


Image by Jeff Hapeman (2010)
"A field of very large Purple Owl's Clover (Castilleja exserta var. exserta ) along California highway 58 in the foothills of the Temblor Range." - Jeff Hapeman
Jeff Hapeman's Flickr page for Castilleja exserta - Purple Owl's Clover

image by Jay Beiler
The other flower I also wonder about is Purple Owl's Clover or (Castilleja exerta) which was always native where I lived up in Anza, but especially on the untouched unmolested areas of Cahuilla Indian Reservation. Mostly large swaths in Terwilliger Valley to the east. The photograph here was taken most likely in 2010 by Jay Beiler of San Diego on the western end of Cahuilla Indian Reservation. If you look closely, you'll see snow capped Mount Jacinto way in the background and the eastern edge of Cahuilla Mountain on the left, so this is looking north. You can see Owl's Clover in among TidyTips, Thistle Chia, California Poppies, Lupines and other natives. Wonder what other plants the Owl's Clover colonizes here ? What roles does it play in meadow biodiversity if any ? This plant, like the Yellow Rattle and Indian Paintbrush is a hemiparasite and like several members of the figwort family, it gains its sugars from photosynthesis but has a poorly developed root system, so it "taps" into the roots of other plants by producing nutrient-absorbing haustoria [like the hyphal strands of mycorrhizal fungi], to obtain some of its water and mineral nutrients.

image: Emmanuel Boulet (2002)
Like the mycorrhizal fungi, they don't really do damage when they send their haustoria type roots to invade within the host plant's root cells as you can see from the photo of a typical type of haustoria here where tissues have been blue stain revealing the light blue cells with the haustoria being the darker blue. Note that it goes through into the tissues, but doesn't puncture the cells. Another benefit besides water and nutrients from host plants are the specific alkaloids that may be produced by some host plants which protect Owl's Clover or Indian Painbrush from predation. lupines have a symbiotic relationship with nitrogen-fixing bacteria and any plant parasitizing them is going to get increased access to nitrogen. Studies have shown that Castilleja using lupines as host experience better growth, increased reproduction, and increased pollen output. Those Lupines in the Anza wildflower mix may even offer some protection from herbivory to Castilleja, as along with nutrients parasites also receive some of the alkaloid lupinine, which is toxic and bitter to animals. This protection may be conferred to the Castilleja, although studies have shown mixed results in whether having lupine as a host actually does decrease herbivory on Indian paintbrush or not. In any event the exchange of differing plant alkaloids between different plants through the underground mycorrhizal grid network is well documented. It's actually been tough to actually search for similar findings with Owl's Clover and Indian Paintbrush as having impacts on biodiversity like the Rhinanthus minor. Either way, it’s clear there are big benefits for these hemiparasitic plants taking advantage of host plants like lupine, and on the Cahuilla Reservation area it’s not uncommon to see the fields full of almost exclusively lupine, Owl's Clover and paintbrush. The Lupines also have their own beneficial symbiotic relationship with bacteria which fix nitrogen from the atmosphere, so nutrition from Lupine hosts is a huge possibility. 

If anything further arises as far as more information on this subject, I will come back and add to the post here
Further Reading References of Interest Family of OROBANCHACEAE
The Population Dynamics and Community Ecology of Root Hemiparasitic Plants. The American naturalist, D. Smith

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