Showing posts with label Nitrogen-fixing bacteria. Show all posts
Showing posts with label Nitrogen-fixing bacteria. Show all posts

Monday, June 1, 2026

Coonties: Florida's only native cycad & only Atala butterfly host plant

Coontie is a popular native for parking lots
like this hospital lot in Jacksonville, because it
doesn't need trimming to maintain this height.

Coontie (Zamia integrifolia), a beautiful & unique plant native to most of Florida & some Caribbean islands, has an interesting history of over exploitation & the near extinction of the Atala butterfly (Eumaeus atala) that depends on this plant as its larval food source. Today, coontie is widely planted in all of Florida because it's attractive, drought-tolerant, salt-spray tolerant, plus it grows in poor soil & does not need trimming. 

Coontie is a Cycad

Cycads are ancient plants that have a fossil record that shows that they have not changed much in the last 68 million years. They are gymnosperms, which means naked seed. (Pines are also gymnosperms.) Angiosperms, the flowering plants with their enclosed ovaries and their pollinators such as bees & butterflies developed much later. 

Cycads bear pollen and ovaries in fleshy cone-like structures at ground level on separate male and female plants. They are pollinated by beetles and the coonties use heat in the cones at different times to attract the beetles to the male cones and then to travel to the heat in the female cones. This is called thermogenesis.

Friday, May 1, 2026

Soil: We Need to Stop Treating it Like Dirt

Gardeners can improve their soil.

Why is soil important for gardeners?

We’ve all heard about growing the right plants in the right places so they’ll survive, but without healthy soil, your plants (even the right plants) will suffer or even die. So let’s look at what’s under our feet.

 (This article is an updated version of one I wrote for a garden blog several years ago, which is no longer available online.)



Healthy soil ecosystems are a complex interaction
 between bacteria, fungi, insects, & more.

Soil: the ecosystem beneath our feet

Soil found in native habitats is a complex ecosystem of bacteria, fungi, nematodes, earthworms, ants, salamanders, toads, insect larvae, moles, and more, all living in a substrate of minerals and humus. The minerals are a mixture of rocks, sand, silt, and/or clay. The humus or organic matter consists of fully or partially digested plant and animal parts. As humus is broken down into simple compounds, it provides a living for the decomposers, and eventually yields nutrients for plants. 

One gram (about 1/5 teaspoon) of healthy, non-poisoned soil could contain one hundred million bacteria, one million actinomycetes (a filamentous bacteria), and one hundred thousand fungi; if strung together, their filaments or hyphae would measure about 16 feet (5 meters) in length. This same gram of soil could also contain hundreds of nematodes living on the damp surfaces of the soil particles and maybe a few insect eggs or larvae and some earthworm cocoons. The exact proportions of each of these organisms will depend on soil conditions such as moisture, acidity, aeration, amount of humus, and the local plant community growing in the soil. 

Sunday, February 1, 2026

Alders Fix Nitrogen

Smooth alder or hazel alder (Alnus serrulata)
Photos by Georgia Native Plant Society

Hazel alder or smooth alder (Alnus serrulata) is blooming now with its showy yellow catkins. The woody female flower heads look like little pine cones. It's a tall multi-stemmed shrub to small tree in the birch family (Betulaceae).

This alder is native to freshwater and brackish water wetlands from Texas to Maine and into North Florida. It plays an important role in these wetlands because it fixes nitrogen in its root nodules using Frankia, a genus of anaerobic, filamentous bacteria in the Actinomycetes order. 

When soil is wet all or most of the time it is anaerobic (without air) and in these conditions, the normal soil microbes cannot survive and most plants cannot obtain enough nutrients from this soil. The alders' symbiotic relationship with this weird bacteria provides the nutrients they need to survive and they do so without much competition from other plants.