Early Fall Weather and Ecological Changes Along the Haw River, NC

One effect of high soil moisture levels is the growth of this Indian pipes or ghost plant.  This used to be considered a saprophyte which has no chlorophyl and breaks down organic matter in the soil.  But a more modern understanding considers it a flowering plant in the family Ericaceae (heaths) which is mycotrophic ( https://www.fs.usda.gov/wildflowers/beauty/mycotrophic/whatarethey.shtml ).  In other words it has an association with specific mycorrhizal fungi which are attached to the roots of green plants and obtains its nutrients in an indirect type of parasitism.  True parasites attach directly to the roots or branches of higher plants.

Early fall is the time for many plants to produce fruits to disperse their seeds.  Some fruits are bright red to induce birds to eat them and deposit them in feces far away.  I give three examples here of dogwood, spicebush and euonymus fruits which seem designed to attract birds with color vision that key on red fruits.  Remember that many mammals do not have color vision and seek food based in large part on smell.  I am especially excited by the prospects of seeing migrating northern thrushes such as Swainson’s and gray cheeked thrushes which will soon be passing through our area and feeding on these fruits.

Speaking of RED colors this is the time for blooms of the cardinal flower, which is designed to attract hummingbirds and butterflies with long tongues.  Such specialized (in contrast to generalized) flowers attract a limited suite of pollinators but get a greater percentage of return visits and cross pollination.  The cardinal flower is also interesting in that it prefers wetland habitats with short hydroperiods, and is protected against mammalian herbivory by toxins.  You will notice in damp pastures that cows and horses do not eat cardinal flowers, ironweed, or sneezeweeds.

Butterflies are still much in evidence on our flowers.  The fall blooming native ironweed have here attracted a pipevine swallowtail.  This is the model toxic species for mimics such as spicebush swallowtails (also toxic) and red spotted purples (not toxic).  I do not see many monarchs but this female is finding nectar on our non-native butterfly bushes, as is a great spangled fritillary.  A cloudless sulphur is attracted to a native coral honeysuckle, a classic hummingbird flower.

Where there are nectar and pollen feeding insects there will be predators.  I enjoy watching two species of spiders especially which have very different methods of catching prey.  The golden garden spider, an orb weaver, has a very interesting web contain a zig zag structure termed a stabilimentum ( https://en.wikipedia.org/wiki/Stabilimentum ).  The function of this structure is uncertain but is thought to involve protection from birds flying through and destroying the web, and attraction of prey by UV reflectance and perhaps male spiders also.   A very different means of prey capture is used by the green lynx spider which sits on the flowers and pounces on prey by ambush.  Since many spiders die in winter and overwinter as eggs, females are attempting to eat as much as possible and grow to a large enough size to lay eggs before frost.  So female green lynx spiders eat an amazing amount of prey and grow very rapidly.  Since they remain more or less in one spot you can watch them over a period of time and see what they are catching.  This particular green lynx female over nine days caught three large prey items- a sphinx moth, a bee fly, and a beetle wasp.  As a result her size increased dramatically.