Caliente Mountain

A warm sky enveloped us at 3900 feet in the Caliente Range. Clear and clean with no wind, perfect weather. The flowers weren’t as good.

Southern slopes were parched and barren in this drought year. There were no colorful blankets. Many of the annuals were smaller than usual. But we found many things of interest and had a really good day.

Caliente Mountain Field Trippers

Marlin, Bob, Lynne, Marti

Lynne Peterson, Marti Rutherford, Diana and Dennis Sheridan, John Chesnut, Marlin Harms, Bob Hotaling, Dirk Walters and myself journeyed up Caliente Ridge.

The photograph shows part of our group.

The shrubs were abundant and pretty healthy: California juniper (Juniperus californica), Tucker’s oak (Quercus john-tuckeri), interior goldenbush (Ericameria linearifolia). And we saw two kinds of mistletoe, one on the junipers and one for the oaks.

Wind Poppy

Wind Poppy

We found List 4 species, such as Calif. androsace (Androsace elongata), Salinas milkvetch (Astragalus macrodon), and Mojave paintbrush (Castilleja plagiotoma). Some other things on the mountain:

  • Amsinckia vernicosa
  • waxy fiddleneck Arctostaphylos glauca
  • big-berry manzanita Boechera pulchra,
  • beautiful rock cress Castilleja subinclusa
  • longleaf paintbrush Caulanthus inflatus
  • desert candle Chenopodium californicum
  • Calif. goosefoot Claytonia parviflora ssp viridis
  • miner’s lettuce Ephedra viridis
  • green ephedra Eriastrum pluriflorum
  • many-flowered eriastrum Eriogonum elongatum
  • long-stem buckwheat Eriogonum fasciculatum var polifolium
  • Calif. buckwheat Erysimum capitatum
  • wallflower Gilia latiflora
  • broad-flowered gilia Leptosiphon parviflorus
  • baby stars Mentzelia pectinata
  • San Joaquin blazing star Monolopia lanceolata
  • hillside daisy Mucronea perfoliata
  • perfoliate spineflower Papaver heterophyllum
  • wind poppy Phacelia distans
  • distant phacelia Phacelia fremontii
  • Fremont’s phacelia Phacelia tanacetifolia
  • fern-leaf phacelia Pholistoma membranaceum
  • white fiesta flower Poa secunda
  • blue grass Stipa speciosa
  • desert needle grass
  • Several kinds of cool beetles pointed out by Dennis Sheridan
Caliente Mountain Field Trip

The rough terrain below Caliente Mountain that we contemplated as we had lunch. The La Panza range is in the distance.

 

 

-George Butterworth, April 14, 2013

Rare Plant Treasure Hunt

Botanical Adventures with the Rare Plant Treasure Hunt!

The Rare Plant Treasure Hunt is a citizen-science program started by CNPS in 2010 with the goal of getting up to date information on many of our state’s rare plants, while engaging chapter members and other volunteers in rare plant conservation.

Many of California’s rare plant populations have not been seen in decades and some parts of the state have seen little to no botanical exploration to date. This program helps conserve our rare flora by providing valuable data to the CNPS Rare Plant Program and the Department of Fish and Game.

Treasure Hunters can join an organized rare plant search or learn how to plan their own trips by attending training events; those who already have some botanical experience can start leading their own trips!

You can also sign up for the mailing list to be notified of upcoming events by sending an email to treasurehunt@cnps.org

Join us for one or more trips this spring/summer! Trips are listed below, and more info can be found at http://www.cnps.org/cnps/rareplants/treasurehunt/calendar.php or by contacting dslakey@cnps.org.

May 5 – Junipero Serra Peak (Monterey Co.)

May 11-13 – Pine Ridge / Tassajara Hot Springs Backpack (Monterey Co.)

May 16 – Sierra Azul Open Space (Santa Clara / Santa Cruz Co.)

May 20 – 22 – Ventana Wilderness Car Camp (Monterey Co.); dates tentative

May 25 – 27 – Cone Peak Car Camp (Monterey Co.)

June 5 – 7 – Pine Ridge Trail / Sykes Hot Springs Backpack (Monterey Co.)

June 8 – Andrew Molera SP (Monterey Co.)

June 14 – 16 – Alder Creek Bot. Area / South Coast Ridge Car Camp (Monterey Co.)

June 28 – 30 – Lion’s Den Bot. Area / Cruickshank Trail Backpack/Car Camp (Monterey Co.)

President’s Message May 2013

Near the end of March Linda and I took off for the central US, mainly to see the mass gathering of sandhill cranes on the Platte River, but also such wonders as the World’s Largest Ball of Twine.

The drought we have been experiencing in SLO is nothing compared to what is happening in New Mexico and Kansas. We have seen wildlife refuges for wildfowl completely devoid of water, no grass left on the range, dry rivers and a host of other problems. Luckily the strange weather produced a later than usual number of cranes, which were a mind-bender.

By the time you read this the annual field trip meeting will have taken place, so think of Kansas if things were not too plentiful. I hope to see you at the May meeting.

-David Chipping

Chapter Meeting May 2, 2013

Chapter Meeting May 2, 2013

Title: Chapter Meeting May 2, 2013
Location: San Luis Obispo Veterans Hall
Description: Thursday, May 2, 2013, 7:00 p.m. at the San Luis Obispo Veterans Hall, 801 Grand Avenue, San Luis Obispo.

Program

Research on the “Hidden Flowers, Cryptantha (Boraginaceae): Recent Insights”

Michael Simpson, Professor of Biology at San Diego State University

Mr. Simpson received his Ph.D. from Duke University. His expertise is plant systematics, including phylogenetic relationships of flowering plants, taxonomy related to species and infraspecies delimitation, and floristic studies. He is the author of the textbook Plant Systematics, 2nd ed. (Elsevier-Academic Press, 2010).

This talk will present recent studies summarizing aspects of taxonomy and phylogenetic relationships of the genus Cryptantha and close relatives. The methodology, evidence, and rationale for splitting the genus into separate genera, all named by previous workers decades ago, will be explained. Current studies and some preliminary results with regard to species and infraspecies definition, including some recent discoveries, will be presented.

Plant ID Workshop

We will be hosting a plant ID workshop from 6:00 to 6:45 p.m. The focus of this mini workshop will be the genus Cryptantha. Dr. Michael Simpson, Professor at San Diego State University and author of The Jepson Manual treatment for Cryptantha will be leading the workshop. Please bring a copy of the new Jepson Manual, if you have one, and a hand lens. Collections of several of our local Cryptantha species will be provided. Workshop participants may also bring in their own Cryptantha collections to identify. Please join us for this exciting opportunity, which is sure to be a fun
and informative event!

Dr. Simpson will provide samples of herbarium specimens and microscope slides with mounted fruits (nutlets) of several species of Cryptantha. Using the key in The Jepson Manual, 2nd ed., participants may practice identification of some of the taxa. Some dissecting microscopes will be provided. See Dr. Simpson’s website for more information about Cryptantha: http://www.sci.sdsu.edu/plants/cryptantha.
Start Time: 19:00
Date: 2013-05-02
End Time: 21:00

California Rare Plants Treasure Hunts

California Rare Plants Treasure Hunts
Join the California Native Plant Society’s Rare Plant Treasure Hunt (RPTH) program in our efforts to search for, document, and help conserve our state’s rarest plants throughout the state.
Check out the trips listed here, or send an email to treasurehunt@cnps.org for help in setting up your own rare plant search!

See the calendar of trips throughout California. For more info, check the RPTH website. To subscribe to updates, send an email to mailto:kclark@cnps.org.

Nicasio Island RPTH

Marin Municipal Water District, Marin County | Saturday March 30th, 2013 | 10AM-3PM

Join the Marin Municipal Water District for a chance to hike on Nicasio Island, which is bound on all sides by the Nicasio Reservoir. This wind-swept island hosts a number of spring-blooming rare plants, so participants will get a chance to add many species to their repertoire. We will search for populations of two different rare lilies (Fritillaria liliacea and F. lanceolata var. tristulis) and use our plant ID skills to figure out if the bluehead gilia (Gilia capitata) belongs to a rare subspecies (ssp. tomentosa). There will also be a chance to view other rare species, such as Iris longipetala and Dirca occidentalis.

Meet at 10AM at the Nicasio Gate, which is on Point Reyes Petaluma Road, about 1 mile west of the intersection with Nicasio Valley Road. Parking is available along Point Reyes Petaluma Road, or in a pullout just east of the Gate. For a map of the gate and parking area, go to http://goo.gl/maps/Af4wb. Be sure to dress appropriately for the weather, and bring water, a lunch, sun protection, and some botany supplies (hand lens, GPS, field notebook, floras). RSVP or send questions to dslakey@cnps.org.

Ano Nuevo State Park RPTH

San Mateo / Santa Cruz Counties | Saturday, April 6th, 2013 | 10AM-3PM

Visit this state park on the San Mateo/SantaCruz Coast to look for several rare species of popcorn-flower (Plagiobothrys). We’ll use our hand lenses to determine the species and subspecies that we find, and will also collect specimens to send to a genus expert from Oregon. We’ll also search for a population of a rare lily, commonly called “stinkbells” (Fritillaria agrestis).

This is a great opportunity for new RPTH participants, as they will learn many valuable skills and tools, such as a background on the CNPS Rare Plant Inventory, use of online botanical resources, practice filling out field survey forms, mapping with GPS units, as well as practice identifying plants with The Jepson Manual and local floras.

Note that the RPTH event at the Moore Creek Preserve has been cancelled, and this trip has been scheduled instead. Meet at the parking area on the west side of Highway 1 that is adjacent to the Cascade Creek Trail (See the State Parks brochure at http://www.parks.ca.gov/pages/523/files/AnoNuevoWebBroch2012.pdf for a map. Be sure to bring a lunch, water, sun protection, and dress for likely windy weather. Also, bring any botany supplies you have, including a hand lens, GPS, camera, field notebook, and floras. Do not leave any valuables in your car, as theft has been a problem at this site in the past. Carpooling from Santa Cruz may be available. RSVP and send questions to dslakey@cnps.org.

Ventana Wilderness – The Indians RPTH

Monterey County (near King CIty) | Friday – Saturday, April 12th-13th, 2013

This is the first in a series of many Rare Plant Treasure Hunts that will take place in the National Forest Wilderness Areas near the Big Sur Coast in 2013. The northern Los Padres National Forest has an incredible amount of plant diversity, including many rare species. For this trip, we’ll do two separate hikes in the vicinity of The Indians Ranch (southwest of King City) to search for both rare plant populations and exotic weed infestations. We’ll look for San Benito fritillary (Fritillaria viridea), Arroyo Seco bush-mallow (Malacothamnus palmeri var. lucianus) and several other plants, depending on which specific hikes we choose.

Participants are welcome to join us at a meeting spot near The Indians Ranch on the evening of Thursday, April 11th, or the morning of Friday, April 12th. We will be car camping at an undeveloped site along Milpitas Rd. Coming out for a single day (Friday or Saturday) is also an option, and carpooling opportunities may be available. Expect hiking to be moderately difficult – we may split into 2 groups to accommodate different hiking abilities. Bring the usual car camping gear, hiking gear, and botany supplies. Contact dslakey@cnps.org for more details and to RSVP.

NorCal trips later in April

April 27th – Lagunitas Meadows (Marin County)

April 27th – Thomes Creek (Tehama County)

April 27th – Lobos Ranch SP (Monterey County)

Look for more details in an upcoming message, or check out details on the event calendar: http://www.cnps.org/cnps/rareplants/treasurehunt/calendar.php

 

Asparagus asparagoides

Asparagus asparagoides

Asparagus Fern or Bridal Creeper

This month’s plant is a South Africa native that has become naturalized in Southern California where there has the potential to become an extremely troubling weed species. It is already considered so in some localities in Southern California, New Zealand and Australia. It had become a major infestation in the oak grove near Lupine Point in the Los Osos Elfin Forest until it was successfully removed after much effort.

The problem with its eradication is obvious from looking at the cluster of corms that form just under ground. If left to multiply, this corm mat forms an extensive, impenetrable mat just below the soil surface that prevents other plant roots from getting to the nutrients they require. A second problem with the corm cluster is that if one just goes out and attempts to pull them up or cut them down, the corms just send up new shoots. One would have to repeat the removal process until the corms have been starved to death. That would be a long arduous process.

The fast and extensive stem and leaf growth is also a problem. It allows the asparagus fern to cover existing plants so well that sunlight can’t get to them.

I asked Bonnie to draw the plant with flower buds only because plants currently available to us are at that stage. I suspect that, if deadlines weren’t a consideration, a plant with fully open flowers might have been found since its blooming period is from December through April. But more importantly, this species’ vegetative state is so distinctive that the smallish, nondescript flowers are often overlooked anyway.

A word of warning, written descriptions of this plant in many books are totally deceptive. First, what looks like leaves are in fact flattened stems, which botanists often term cladodes. Unfortunately I also ran across several other technical terms for them.

How does one know they are “flattened stems” and not what they actually look like – “leaves.” All vascular plants have the same leaf-stem morphology. First the stem is divided into alternating nodes where the leaves are attached and internodes where there are no leaves. The exterior nodal structure includes the leaf and a bud found in the upper angle between the leaf base and the stem. When the bud germinates it produces a new stem which then can produce more leaves. This means that a given portion of stem produces a leaf only once or leaves are produced only during the first year of that particular stem’s life.

Remember, buds produce new stems only. So a reexamination of Bonnie’s drawing shows the green flattened stems (cladodes) arising from the angle of a small grayish scale. That scale is all there is to the true leaf. Using flattened stems for leaves is considered an adaptation to drought conditions.

As an example of how confusing this can be, look at the identification keys in the New Jepson Manual. The keys from group to family to genus to species all assume that you know that the leaves are those tiny, insignificant, hardly visible scales under the things that everyone but a botanists would assume where leaves but aren’t.

Bonnie has drawn a couple of flower buds coming from the axil of leaf whose bud grew into the cladode. Examine the node again very carefully. You will note that there are actually three scales visible. The largest one is the leaf and the two smaller ones just visible are the bracts (leaves associated with flowers) whose buds germinated to produce the flowers. Botanists consider flowers to be highly modified leafy branches. Why they think this must be the subject for another time. Oh yes, that means this plant must produce 3 leaves and buds per node. Two of them only develop when that node produces flowers, otherwise they would be invisible.

The plant has a number of common names as might be expected of a plant used by humans. Its primary use is in floral arranging. Its thin stem and abundant dark green cladodes together give it a kind of filmy or ferny appearance which explains the “asparagus fern” name.

Its long use in bridal bouquets explains its African bridal creeper, bridal-veil creeper, or merely bridal creeper names. Other names that I’ve seen include Gnarboola, Smilax or Smilax asparagus. The last two names should be forgotten as they indicate it is related to the genus, Smilax, which it is not. I assume Gnarboola is its name in its native Southern Africa. The genus, Asparagus, belongs to a group of monocots that produce flowers with a perianth of six sterile elements that are more commonly called sepals and petals.

This genus’ flowers have 3 greenish-white sepals and 3 identical greenish white petals. When sepals and petals are identical except for position (sepals are always the outer whorl and petals interior to the sepals) botanists use the term “tepals.” There is a large assembly of tepal plants including the lilies, amaryllis, tulips, onions, and garden asparagus. The list could go on and on. The problem with this group is that all their flowers are built on the same plan and whenever this happens taxonomist often can’t agree on family or even ordinal boundaries. For example, a search on my library and internet finds this genus placed in the lily family (Liliaceae – order Liliales) or the Asparagus family (Asparagaceae – Asparagales). Added to this the current distinction between these orders has to do with different DNA sequences and unique chemical constituents found in their seed coats, neither of which are hardly field characters. For the record, the new Jepson Manual puts this plant in the Asparagales and the Asparagaceae.

by Dirk Walters, illustrations by Bonnie Walters | Dirk and Bonnie Walters are long-time CNPS-SLO members, contributors, and board/committee participants. In addition to his work at Cal Poly, Dirk is the current CNPS-SLO Historian.
SOD Blitz 2014

SOD Blitz 2014

Sudden Oak Death (SOD) Blitz

SAVE THE DATE

Sudden Oak Death (SOD) Blitz – May 16, 17, and 18, 2014

What is Sudden Oak Death (SOD)

Sudden Oak Death (SOD), a serious exotic disease, is threatening the survival of tanoak and several oak species in California. As of 2013, SOD is found in 14 coastal California counties, from Monterey to Humboldt.

Researchers have discovered that Phytophthora ramorum, the pathogen that causes SOD, spreads most often on infected California bay laurel leaves. Some management options are available, but they are effective only if implemented before oaks and tanoaks are infected; hence, timely detection of the disease on bay laurel leaves is essential for a successful proactive attempt to slow down the SOD epidemic.

Purpose of SOD Blitz

The SOD Blitz informs and educates the community about the disease and its effects, gets locals involved in detecting the disease, and produces detailed local maps of disease distribution. The map can then be used to identify those areas where the infestation may be mild enough to justify proactive management.

San Luis Obispo SOD Blitz, 2013

In May 2013, 14 people (mostly SLO CNPS Chapter members) conducted a SOD Blitz sampling event. A total of 872 trees were surveyed and samples were collected from 89 trees. There were no SOD positive trees found during this survey.

  • A community meeting/training session held on a Friday evening; followed by collection of leaf samples by volunteers on Saturday and Sunday.
  • Samples and accompanying forms are then turned in at a central location Saturday and Sunday afternoon/evenings.
  • We will provide a list of recommended areas for sampling at the meeting.
  • We will divide into groups for collecting. Ideally, one person in a group will have a GPS device or tablet or phone with GPS capability.

San Luis Obispo SOD Blitz 2014

We need to continue the sampling in 2014 and need volunteers to attend the training and collect samples in May 2014.

Training

Friday, May 16, 7pm to 8:30pm, SLO County Department of Agriculture, 2156 Sierra Way, San Luis Obispo, CA


View Larger Map

Collecting

Saturday and Sunday, May 17 and 18 (Locations TBD). All of the materials necessary for training and collecting will be provided.

The training is free although space is limited – If you are interested, please submit your name and contact info to:

Lauren Brown lbrown805@charter.net , (805)460-6329, or

Kim Corella (fmr. Camilli) kim.camilli@fire.ca.gov, (805) 550-8583

For additional information on SOD and the SOD Blitz project, please visit http://www.sodblitz.org.

Special thanks to all of you who contributed and participated in 2013 and I look forward to having the same level of participation in 2014.

– Lauren Brown, SLO Chapter Invasive Plants Committee

 

 

Sudden Oak Death Blitz 2013

May 3, 4 and 5, 2013

San Luis Obispo

Friday, Saturday and Sunday

Sudden Oak Death (SOD), a serious exotic disease, is threatening the survival of tanoak and several oak species in California. Currently SOD is found in 14 coastal California counties, from Monterey to Humboldt.

Researchers have discovered that Phytophthora ramorum, the pathogen that causes SOD, spreads most often on infected California bay laurel leaves. Some management options are available, but they are effective only if implemented before oaks and tanoaks are infected; hence, timely detection of the disease on bay laurel leaves is key for a successful proactive attempt to slow down the SOD epidemic.

The purpose of the SOD-blitz is to inform and educate the community about the disease and its effects, get locals involved in detecting the disease, and produce detailed local maps of disease distribution. The map can then be used to identify those areas where the infestation may be mild enough to justify proactive management. A community meeting/training session will be help on a Friday evening; followed by collection of leaf samples by volunteers on Saturday and Sunday. Samples and accompanying forms are then turned in at a central location Saturday and Sunday evenings. Additional information will be included in the next newsletter, or you can visit the website: http://www.sodblitz.org.

Training – Friday, May 3, 6:30 to 8:30 p.m. at SLO County Department of Agriculture (2156 Sierra Way, San Luis Obispo)

Collecting – Saturday and Sunday, May 4 and 5 (Locations TBD).

All of the materials necessary for the training and the collecting over weekend will be provided.

If interested, please contact: Lauren Brown – lbrown805@charter.net or (805)460-6329

Thank you.

– Lauren, Chair Invasive Species Committee

LOST ITEM

I lost an antique silver serving fork at the banquet. It was with the ham.

If you’ve seen it or have any information, please call 528-0446 or email CNPS Booklady.

Thank you, Heather Johnson

 

Amanita phalloides

Amanita phalloides

Why is the Death Cap mushroom so deadly?

On New Year’s Day I visited a favorite, and normally productive, chanterelle patch outside San Luis Obispo to discover an enormous fruiting of the dangerously toxic death cap mushroom (Amanita phalloides).

My culinary disappointment was tempered by my growing fascination with the question, “Why are mushrooms deadly poisonous?” Proximally, the answer is direct: because they contain a peptide, alpha-amanitin, which halts RNA transcription in the cell nucleus. In broader context, the question should be rephrased, “What ecological advantage and evolutionary fitness does the presence of this toxin contribute?”

Amanita phalloides is a newcomer to California. It is known to be a native of Europe, and its first verified collection in California dates to 1938. Anecdotally, its introduction is ascribed to an accidental arrival on the roots of cork oak trees. It is now known from Southern California to British Columbia. A similar introduction (on the roots of Italian chestnuts?) affects the East Coast.

Death cap is an ectomycorrhizal symbiont. This means it forms connections on the root-tips of forest trees; in California, its typical (but not exclusive) partner is coast live oak. Unlike many symbionts which are highly host specific, death cap is promiscuous in its associations as it spreads worldwide. It is now present in South Africa, Australia and most other similar climes.

Ectomycorrhizal (EC) fungi collect major nutrients, nitrogen and phosphorous, and exchange these with the host tree for sugars. Delicate hyphal strands extend outward from the root tip mass into the surrounding soil and mulch. EC also allows efficient active transfer of macronutrients, micronutrients, and soil water to the tree. The chronic phosphorous limitation in serpentine soils makes the EC symbiosis especially important for local forest types on this soil. Studies in Norway discovered up to 50% of a birch tree’s sugar is exchanged at the root tips with EC symbionts.

Death Cap - Amanita phalloides

Death Cap – Amanita phalloides

Other studies describe how a mushroom, Laccaria bicolor, lures springtail insects (Folsoma candida) into traps, consumes them, and transfers the nitrogen obtained to its host tree.

Trees form non-exclusive associations with many fungi. Studies at Pt. Reyes show more than 15 taxa of EC fungi present at the root tips of coast live oak from a single grove. Most of the live oak symbionts are not deadly or even dangerous, and include the sought after chanterelles.

It is an entirely open research question as to whether the recent invasion of Amanita phalloides into the California oak forest is supplanting native fungi. Studies (in Bishop pine) have shown that EC fungi partition their habitat niches very precisely, allowing multiple fungi to coexist in close proximity. I have visited the particular chanterelle patch since the 1970’s without noticing the Aman5.0ita, so the 2012 fruiting might possibly represent a replacement of one symbiont for another, or just be a fortuitous fruiting of an established co-dominant.

The “competitive exclusion principle” argues that if these organisms are competing within the same precise niche, the most successful will replace all others. The deadly toxin of Amanita’s is alpha-amanitin. This is a heat-stable cyclic peptide that interferes with the transcription function of RNA in the nucleus of cells of virtually all organisms.

Humans, dogs, rabbits, and guinea pigs are equally poisoned. The toxic crisis is caused by irreversible liver or kidney damage, as the molecule concentrates in those organs. More expansively: organisms other than bacteria are affected by alpha-amanitin. Insects, worms, flowering plants, and even viroids (infectious single strands of RNA) that cause “mad cow” and disease in plants cannot replicate when treated with amanitin.

Amanitin is a large, very stable molecule (C39H54N10O14S) so it represents a significant metabolic cost to the fungus to create. Several, widely unrelated, taxa of gilled mushrooms possess amanitin toxin, so its synthesis has been separately evolved several times in fungi –supporting the assumption this represents an important competitive innovation for the species. Fortunately, amanitin is too large to cross the blood/brain barrier, so even victims with irreversible liver and kidney damage due to mushroom poisoning are not affected mentally.

An evolutionary entomologist working in New York State, John Jaenike, has discovered four species of mushroom flies in the genus Drosophila that lay eggs in the gills of fruiting Amanita phalloides. The fruit fly taxa are related to ones that inhabit rotting skunk cabbage, but in New England have recently transferred to the recently introduced Amanita fruitings.

Jaenike discovered that Amanita phalloides is toxic to the damaging parasitic nematodes Howardula that reproduce in the stomach of fruit flies. The toxicity of the death cap to the parasitic nematodes results in much greater egglaying (fecundity) by the fruit flies. The fruit flies are affected by the toxic amanitin, especially the males, but the poison is more than offset by the increase in reproduction.

Janike also discovered that most other insects using mushrooms as egg laying sites (craneflies and forest gnats) shun use of the Amanita (due to its toxicity).

Fruiting mushrooms are a scarce and erratically scattered resource for reproduction and larval feeding. Fruiting mushrooms are fully and completely consumed by mushroom gnat larvae, and Jaenike postulates fierce competition for insect breeding sites. Jaenike has published several papers describing the Amanita-Drosophila-Howardula food web. Mushroom flies secured a niche free of competition by exchanging an evolved tolerance to sub-lethal poisoning for escape from nematode parasitism. The increased fitness leads to greater egg-laying ability, and has provided the evolutionary inertia for this recent adaptation.

Nematodes are significant pests of commercial mushroom production, epidemic infestation can result in the loss of the growing beds. The oyster mushroom, Pleurotus osteraceus, traps and consumes nematodes in noose-like knots of hyphal tissue.

So why are Amanita so poisonous? It is an unlikely deterrence to vertebrate predation of the fruiting caps, as the effect is slow-acting (36-72 hours before the toxic crisis in humans) and the toxin is not concentrated in the cap. Evidence supports the hypothesis that the fitness obtained from synthesizing the toxin is secured within the hyphal network. Perhaps toxic Amanita obtain nitrogen from poisoned nematodes, or protect themselves (and their symbiont hosts) from plant parasitic nematode predation.

Perhaps the toxin suppresses the growth of competing fungal webs. It seems clear the toxic effect of death cap is intrinsic to its invasive success worldwide.

John Chesnut | Rare Plant Coordinator and Education Committee at CNPS-SLO, John teaches horticulture at Cal Poly

Sources:

Jaenike, J., “Parasite Pressure and the Evolution of Amanitin Tolerance in Drosophila,” Evolution,Vol. 39, No. 6 (Nov., 1985), pp. 1295-1301. Jaenike, J. and T J. C. Anderson, “Dynamics of Host-Parasite Interactions: The Drosophila-Howardula System,” Oikos Vol. 64, No. 3 (Sep., 1992), pp. 533-540. http://web.uvic.ca/~stevep/pdfs/AmNat_02.pdf

Pringle, Anne, and Else Vellinga, “Last chance to know? Using literature to explore the biogeography and invasion biology of the death cap mushroom Amanita phalloides.” http://www.msi.harvard.edu/downloads/teacherworkshop/Readings/Ben_Papers%20_TWS/Pringle%20and%20Vellinga%202006.pdf

Pringle, Anne, Rachel I. Adams, Hugh B. Cross, and Thomas D. Bruns, “The ectomycorrhizal fungus Amanita phalloides was introduced and is expanding its range on the west coast of North America,” Molecular Ecology (2009). http://arnarb.harvard.edu/faculty/pringle/pubs/Pringle_MolEcol_2009.pdf

Wolfe, Benjamin E., Franck Richard, Hugh B. Cross, and Anne Pringle, “Distribution and abundance of the introduced ectomycorrhizal fungus Amanita phalloides in North America,” New Phytologist (2009). http://www.oeb.harvard.edu/faculty/pringle/documents/Wolfe_Ap_Distribution.pdf

Wieland, Theodor and H. Faulstich. Amatoxins, Phallotoxins, Phallolysin, and Antamanide: The biologically Active Components of Poisonous Amanita Mushrooms. http://informahealthcare.com/doi/pdf/10.3109/10409237809149870

Horton, Thomas R., and Thomas D. Bruns, “The molecular revolution in ectomycorrhizal ecology: peeking into the black-box,” Molecular Ecology (2001)10, 1855–1871. http://www.cnr.berkeley.edu/brunslab/papers/

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