Erythronium

Erythronium hendersonii

Erythronium is one of my favorite genera of wildflowers. This year, for some reason, they are blooming prolifically to the delight of bees and myself alike! Honeybees, bumblebees, and anthophorine bees (Anthophora or Habropoda) are visiting the flowers of Erythronium hendersonii, and surely other species, feverously. I expect this year to be one of the best for seed production, the primary mode of reproduction (as opposed to vegetative increase) for E. hendersonii and oregonum, two species which I've been fortunate enough to observe directly in habitat this year.

Erythronium hendersonii

A short introduction for those not introduced to this genus: There are around 20 to 31 species in all, many from the Western US, a few in the Eastern US, and a some in Eurasia. They are in the lily family (Liliaceae), and so related to Fritillaria, Lilium, and Tulipa among others. These are mostly Spring ephemerals, though some of the alpine and subalpine species bloom in the Summer as the snow melts. They grow from bulbs (some say corms), with tunics that don't seem to cover the entire bulb, thus they are susceptible to drying out. Contractile roots pull the bulbs down deeply, perhaps to help them evade herbivores (voles, etc.) and to keep them from desiccation is Summer.

Erythronium hendersonii mottled leaf. E. oregonum is similarly mottled.

Many of the species have mottled or spotted leaves, some plain green. In general, mottled leaves are found in species growing in the West while spotted leaves are found in species in the East and Eurasia. Flowers are often born singly (sometimes in clusters in mature and happy plants, and nearly all species have flowers that face downwards (except Erythronium rostratum, a yellow-flowered American forest dweller of the central-southern states). Most are probably bee pollinated, though they aren't specialized and can probably be pollinated by a variety of insects, including flies.

Erythronium hendersonii, one anther dehisced

The pendant flowers have multiple beneficial consequences. First is to exclude inefficient pollinators, since pendant flowers are difficult for many insects to land on (beetles or butterflies, for example, struggle to land on fully pendant flowers). Bees are the primary pollinators of Erythronium, though flies are certainly capable of pollinating the open flowers and may be of special importance in forest dwelling and alpine species where bees are not always as abundant. Pendant flowers also have the advantage of being protected from rain. The pollen is dehisced over a relatively delayed period since the anthers don't open all at once. In general, three anthers will open first while three will open days after the first three. This lessens the chance that hard rain or wind will damage the pollen. The recurved tepals further protect the flower by closing or bending down in rain or in diminished sunlight, then opening up again when the sun comes out.

Erythronium oregonum ssp. leucandrum

Bulbs always seem to grow deeper than one would think, and digging wild plants is likely to kill them (besides being an unethical practice). Fortunately, Erythronium is relatively easy to grow from seed. Seed of most species can be sown in Autumn on the surface of the potting medium. As per advice from friend and bulb grower extraordinaire Ian Young, soaking the seeds overnight in water improves the first year germ rate. I have found this to be accurate, as seed I had acquired of a handful of species was successfully sown this way. Left outside throughout Winter, all of my Erythronium seed pots have germinated. I will allow them to grow on for another year before repotting them or planting them out into the garden. As stated, neither E. hendersonii or oregonum increase reliably vegetatively and are best increased by seed.

Erythronium hendersonii seedlings

A species from Eastern North America, yellow-flowered Erythronium americanum, has been heavily researched. In a handful of studies, mycorrhizal relationships between E. americanum and associated plants were examined. The most exciting discovery, in my opinion, was that bulbs (or as they say, corms) infected with arbuscular mycorrhizal fungi which enters the roots, unlike ectomycorrhiza which doesn't enter the roots, were found to be nearly twice as large as bulbs treated with fungicide. E. americanum produces roots in the Autumn, as do all Erythronium, and it is then that they are infected. Surrounding plants and trees, such as sugar maple (Acer saccharum) grow in close association with E. americanum and have been found to share mycorrhiza. Another interesting discovery was that E. americanum may help the establishment of young sugar maples by supplying them with carbon through the mycorrhizal network. Ian Young wrote a concise piece on the seeds of Erythronium, including how to grow them, found here: Erythroniums in Cultivation: Seeds (Ch.1). As an aside, the bulbs are supposedly edible, though I couldn't bring myself to eat something so beautiful (and I discourage anyone from eating wild or unfamiliar plants for ethical and safety concerns).

Erythronium hendersonii in habitat

I speculate that other species of Erythronium also participate in mycorrhizal networks, and that they benefit from the infection as well. Many of the trees and shrubs that grow in association with Erythronium hendersonii and E. oregonum benefit from or require mycorrhiza (Acer sp., Arbutus menziesii, Arctostaphylos viscida, Ceanothus sp., Quercus sp., Pseudotsuga menziesii, etc.), therefore it is not inconceivable that they too benefit from mycorrhizal associations.

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Erythronium oregonum

Erythronium oregonum ssp. leucandrum, differentiated from the type by having white anthers.

I had recently discovered, entirely by accident, a small population of Erythronium oregonum ssp. leucandrum on a nearby mountain above a small creek. It was my first encounter with the species in Oregon, the wild, or anywhere. The air was moist, no doubt in result of the running water complete with a small waterfall, and it was cool. In small clearings of Arbutus menziesii, Pseudotsuga menziesii, leafless Quercus, small groups of E. oregonum were awaiting discovery. There were a few individuals of E. hendersonii, though not many. There are conflicting reports of whether the two species hybridize. I didn't see any hybrids, though I did see the species growing in close vicinity. The more adaptable E. hendersonii ventured slightly into the woods, while the more picky E. oregonum was solely found in forest clearings.

Erythronium oregonum ssp. leucandrum, greenish reverse

Erythronium oregonum ssp. leucandrum with a dance fly (Empididae), a potential pollinator

Erythronium oregonum ssp. leucandrum, nectar guides

Erythronium oregonum ssp. leucandrum in habitat

Erythronium oregonum ssp. leucandrum

Erythronium oregonum ssp. leucandrum with Toxicodendron (no leaves yet)

Erythronium oregonum ssp. leucandrum in habitat

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Erythronium hendersonii

Erythronium hendersonii and Apis mellifera

Since I have lived in Oregon, Erythronium hendersonii has been a favorite wildflower of mine. Compared to E. oregonum, it is more common in hotter and drier areas, and prefers forest edges to cool shady clearings. This could explain the lack of hybridization, the two seem to prefer distinctly different habitats. This year has been a particularly floriferous year for E. hendersonii, and it is the first year I've seen honeybees visiting the flowers. The typical pollinators, based on my observations, are species of Bombus and anthophorine bees. More photos and information can be found on the Pacific Bulb Society page: Erythronium hendersonii.

Erythronium hendersonii

Erythronium hendersonii

Erythronium hendersonii, an aging flower.

Erythronium hendersonii, one anther just beginning to open.

Erythronium hendersonii

Erythronium hendersonii, aphids on the scape.

Erythronium hendersonii, large and small morphs.

Erythronium hendersonii, anthers shorten after opening.

Erythronium hendersonii, true petals (inner) ridged, sepals (outer) mostly flat.

Erythronium hendersonii leaves.

Erythronium hendersonii, a particularly happy roadside cluster. I find this kind of growth uncommon.

Erythronium hendersonii nectar guides.

Erythronium hendersonii

Erythronium hendersonii

Erythronium hendersonii, interesting reverse coloration.

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References:

Alverson, Ed. "My Erythronium "Big Year"" Scottish Rock Garden Club. May 2006.http://www.srgc.org.uk/monthfeature/june2006/content.html 

Lapointe, Line, and Sylvain Lerat. "Annual Growth of the Spring Ephemeral Erythronium americanum as a Function of Temperature and Mycorrhizal Status." Can. J. Bot. 84.1 (2006): 39-48.https://goo.gl/ViL1t3 

Lerat, Sylvain, Rachel Gauci, Jean Catford, Horst Vierheilig, Yves Piché, and Line Lapointe. "¹⁴C Transfer between the Spring Ephemeral Erythronium americanum and Sugar Maple Saplings via Arbuscular Mycorrhizal Fungi in Natural Stands." Oecologia 132.2 (2002): 181-87.http://goo.gl/b0RAXU 

Owen, Travis, et al. "Erythronium hendersonii." Pacific Bulb Society. 2015.http://www.pacificbulbsociety.org/pbswiki/index.php/Erythronium_hendersonii 

Young, Ian. "Erythroniums in Cultivation: Erythronium oregonum (Bulb Log 49)." SRGC Bulb Log. 9 Dec. 2015.http://www.srgc.org.uk/logs/logdir/2015Dec091449666371BULB_LOG_4915.pdf 

Young, Ian. "Erythroniums in Cultivation: Erythronium hendersonii (Bulb Log 51)." SRGC Bulb Log. 23 Dec. 2015.
http://www.srgc.org.uk/logs/logdir/2015Dec231450868200BULB_LOG_5115.pdf