(Quentin Cronk, Director of the UBC Botanical Garden and Centre for Plant Research has kindly offered to guestblog today -- Daniel)

A crabspider (Misumena vatia) is here seen capturing a bumble bee (Bombus sp.) on the rare Kincaid's lupin (Lupinus sulphureus subsp. kincaidii) in the Willamette Valley, Oregon. Kincaid's lupin is interesting as it is the host of the even rarer Fender's Blue Butterfly. The lower flowers of the Kincaid's lupin are turning brown. Surprisingly, this is natural pigmentation and not an indication that the flowers are dying. Another rare plant of the Willamette Valley, the thin-leaved peavine (Lathyrus holochlorus), has the same brown colour in the petals but both the function and the biochemical basis of this trait are unknown. Photographs of some of the Rare and Endangered Plants of the Willamette Valley are available online, thanks to the Institute for Applied Ecology. The Willamette Valley in Oregon is a fertile mosaic of drained farmland interspersed with remnant wetlands of immense nature conservation importance.

(I'm adding this part -- Daniel). Nature resource link: David Neiwert, a Seattle-based freelance journalist, has posted a written and photographic account of his recent experience with killer whales near Vancouver Island. A bit off-topic for this weblog, perhaps, but I can't help but share this fine piece of nature writing.

Updated September 30, 2005 at 10:22 pm: This entry was Botany Photo of the Day's contribution to the first-ever Circus of the Spineless, a monthly gathering of online essays and photographs about invertebrates.

The discovery of this caterpillar on a Nothofagus antarctica (southern beech) tree in the alpine garden yesterday provoked some excitement among the staff (and a comment that it has good taste in trees). Eight centimetres long and as thick as my forefinger, this caterpillar is the larval stage for the polyphemus moth (more, with distribution map). Leaves of deciduous hardwood trees and shrubs form the diet of this caterpillar. It has been observed that the caterpillar cuts the petiole of leaves it has skeletonized, so that (purportedly) no traces of its presence remain on the tree to alert predators.

Antheraea polyphemus belongs to the subfamily of moths known as the saturnids (Saturniidae), or giant silk moths. The Saturniidae, it can be argued, are the most striking of moths. Photographs of moths in this subfamily can be seen here: Saturniidae Moths from Thailand and the What's That Bug? gallery of saturnids.

Entomology / Botany resource link: Caterpillars of Pacific Northwest Forests and Woodlands. The life cycles of plants and insects are often intertwined, so knowledge of insects can give depth to understanding of plants; this link provides details on caterpillar morphology and ecology, as well as keys for identification.

“Pine-cone willow gall” is caused by a gall midge, Rhabdophaga strobiloides. This dipteran (related to flies and mosquitoes) deposits an egg in the developing terminal leaf buds of the willow in early spring. The larva releases a chemical which interferes with the typical leaf and branch development of the willow, instead causing the formation of this cone-like structure. The adult dipteran emerges the following spring, after having spent the winter in the gall.

Check out a few more photographs of pine-cone willow gall via the Cornell Plant Pathology Herbarium or read more about galls courtesy of the Michigan Entomological Society. Douglas Justice has also identified the phenomenon in the past on the garden's discussion forums.

I'm a fan of trembling aspen. Few plants can be said to make a memorable noise or movement, but the flutter of aspen leaves in a breeze is oft a subject of prose, including Shakespeare.

The culprit behind the designs on these leaves is another matter. I believe no one has yet written “An Ode to Phyllocnistis populiella”, the aspen serpentine leafminer. The larva of this moth will tunnel and eat its way through both the spongy mesophyll and the chlorophyll-dense palisade mesophyll of a leaf, leaving behind a whitened snake-like pattern bisected by a brown trail of excreta.

When there is a mass infestation of aspen serpentine leafminers, whole stands of trembling aspen will change from green to silver in appearance. This is what I observed in the area surrounding Merritt, British Columbia, a couple weekends ago, and I regret not getting a landscape shot of these “silver ghosts”. It was a phenomenon I'd never seen before.

However, it seems like I'll have more opportunities in the future. It has been anecdotally reported that mass infestations are on the increase, speculatively due to a rise in winter mean temperature (source: “Leafminer Impacts on Photosynthetic Ability of Populus tremuloides” (PDF), a research paper by Kaarle Strailey as part of coursework at Berkeley).