In the fall, one of my favorite plants is the Eryngo
Our local Eryngo is Eryngium leavenworthii which is an annual plant known commonly as Leavenworth’s eryngo. It is native to the central United States. It reaches heights of up to 3 feet that inhabits dry rocky praries, roadside fields, open woodlands and waste areas. It is mostly seen flowering between July to September, however in some areas it has been seen blooming as late as November. The flowers are atop spiked leaves and elongated stems and form cones of purple or wine colored, tightly clustered blossoms that resemble fuzzy pineapples. The plant is mostly found in areas with limestone or chalk soils. It is in the parsley family and was named after its discoverer, Melines Conklin Leavenworth (1796-1862).
We were out looking for birds, flowers, plants and insects when we discovered this area with some great plants and spiders.
We saw numerous Eryngos growing in the fence row, but what was amazing, was there were numerous Argiope spiders associated with them. We saw a spider between almost every pair of fence posts. What was even more amazing was that almost every spider was on the side of the web away from the fence. The location was the South county line road of Tarrant County. The wind is mostly out of the South during the summer and fall, so my guess is that the flying insects or grasshoppers would hit on the side with the spider. This fence was on the edge of the prairie with limestone and chalky soils. We must have seen 30-40 big spiders in just a few hundred yards.
Eryngium is a genus of about 230 species of annuals and perennials with hairless and usually spiny leaves, and dome-shaped umbels of flowers resembling those of thistles. The genus has a cosmopolitan distribution, with the centre of diversity in South America. Some species are native to rocky and coastal areas, but the majority are grassland plants. Common names include Sea-holly and Eryngo, the former typically being applied to coastal species, and the latter to grassland species.
The flowers are clustered in tight umbels, with a whorl of spiny basal bracts.
Many species are grown as ornamental plants in gardens, and these may also be called “sea holly”, though the majority are not associated with littoral (sea-shore) habitats. Among the best known of these is Eryngium bourgatii, a perennial with stunning green, prickly foliage marbled with silver. The flowers, which appear in summer, are cobalt blue, and appear very attractive to bees. The plant is 30 to 60 cm in height. Other commonly grown ornamental species include Eryngium alpinum, E. variifolium, E. tripartitum, E. bromeliifolium, and the biennial E. giganteum.
For a distribution of all species of Eryngium in the US and Canada, go here to the USDA Plant Database.
Look below the master Genus map and you can see which native species your state has.
There are a lot of species with radically different appearances.
Take a look. It will be worth your time. I discovered quite a few that I was not familiar with.
I was looking up the Chiricahua Mountain eryngo, Eryngium lemmonii, which is found in New Mexico and Arizona, when I ran across this interesting, feel-good story about wildflower identification.
Linda Ford in Mexico’s Copper Canyon Region.
Go to the bottom of the page and click on the thumbnail of the ‘Mexican Thistle’ or Eryngium lemmonii.
A striking plant.
Now for ‘spider talk’ and a note or two about the Argiope aurantia.
The spider species Argiope aurantia is commonly known as the Black and Yellow Garden Spider, Writing Spider, Banana Spider or Corn Spider. It is common to the lower 48 of the United States, Hawaii, southern Canada, Mexico, and Central America. They have distinctive yellow and black markings on their abdomens and a mostly white cephalothorax. Males range from 5 to 9 mm; females from 19 to 28 mm. Like other members of Argiope they are considered harmless to humans.
Garden Spiders often build webs in areas adjacent to open sunny fields where they stay concealed and protected from the wind. The spider can also be found along the eaves of houses and outbuildings or in any tall vegetation where they can securely stretch a web. The circular part of the female’s web may reach two feet in diameter. Webs are built at elevations from two to eight feet off the ground.
Female Argiope aurantia spiders tend to be somewhat local, often staying in one place throughout much of their lifetime.
The web of the yellow garden spider is distinctive: a circular shape up to 2 feet in diameter, with a dense zigzag of silk, known as a stabilimentum, in the center. The purpose of the stabilimentum is disputed. It is possible that it acts as camouflage for the spider lurking in the web’s center, but it may also attract insect prey, or even warn birds of the presence of the otherwise difficult-to-see web. Only those spiders that are active during the day construct stabilimenta in their webs.
To construct the web, several radial lines are stretched among four or five anchor points that can be more than three feet apart. The radial lines meet at a central point. The spider makes a frame with several more radial lines and then fills the center with a spiral of silk, leaving a 5/16″ to 3/8″ gap between the spiral rings, starting with the innermost ring and moving outward in a clockwise motion. To ensure that the web is taut, the spider bends the radial lines slightly together while applying the silk spiral. The female’s web is substantially larger than the male’s, who builds a small zig-zag web nearby. The spider occupies the center of the web, usually hanging head-down, waiting for prey to become ensnared in the web. If disturbed by a possible predator, she may drop from the web and hide on the ground nearby. The web normally remains in one location for the entire summer, but spiders can change locations usually early in the season, perhaps to find better protection or better hunting.
The Garden Spider can oscillate her web vigorously while she remains firmly attached in the center. This action might prevent predators like wasps and birds from drawing a good bead, and also to fully entangle an insect before it cuts itself loose.
In a daily ritual, the spider consumes the circular interior part of the web and then rebuilds it each morning with fresh new silk. The radial framework and anchoring lines are not usually replaced when the spider rebuilds the web. The spider may be recycling the chemicals used in web building. Additionally, the fine threads that she consumes appear to have tiny particles of what may be minuscule insects and organic matter that may contain nutrition.
USDA, NRCS. 2009. The PLANTS Database . National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
Reference for Eryngo and Argiope:
Wikipedia was once considered a poor man’s encyclopedia,
but has evolved into a nice reference for the Naturalist in search of general information.