dissemination mechanism?

Jane McGary janemcgary@earthlink.net
Fri, 20 Sep 2013 13:04:21 PDT
Richard wrote

>Been looking at Lilium washingtonianum at northern limit of range in 
>Oregon. A very robust plant growing often in bare road cuts, ie sub 
>soil and dry habitat, in this area 4000 feet elevation or close. 
>Encroaching vegetation is Alnus sinuata another pioneer plant 
>eventually young conifers, and other shrubs. Of 5 sightings one was 
>in established conifer community. Is this lily and other L. spp 
>pioneer species? Query relates to restoration efforts.

As Richard noted, the native Pacific Northwest lilies Lilium 
washingtonianum and Lilium columbianum are often seen in flower at 
forest margins, next to trails and road cuts. I've also noticed L. 
columbianum flowering profusely in areas that were clear-cut a few 
years earlier. It's likely that seed of lilies and other plants can 
germinate much more easily in the disturbed soil of such sites, which 
would qualify them as "pioneer plants," but in the case of the 
lilies, it's also possible that they were present as non-flowering 
plants for many years and flowered when they were able to put on a 
growth spurt with extra sunshine and nutrients from soil disturbance. 
Trillium ovatum also does this, as I noticed when I had an access 
cleared into the forest on my former property. So does the endemic 
Clackamas Iris, Iris tenuis, which persists in the forest without 
flowering but bursts into bloom on road cuts and under the 
high-tension power line where we usually take visitors to see it.

An interesting case among bulbous plants is Erythronium elegans, an 
endemic of a couple of mountaintops in the Oregon Coast Range. Its 
habitat is slowly being overgrown by trees, partly because it's 
protected, and we see the Erythronium in flower only in the clear 
areas. Fortunately, the Mount Hebo population grows partly on a very 
steep slope where trees are not likely to take hold, but as the 
forest encroaches under the influence of global warming and fire 
suppression, the last strongholds of this species are under threat.

Observations like these tell us that "shade plants" might more 
usefully be called "shade-tolerant plants," and that in some regions 
they may perform better given more sun. I think this is especially so 
when we bring the plants into gardens north of their native range.

Jane McGary
Portland, Oregon, USA

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