Yesterday's walkabout in the garden yielded the discovery of only a few scattered and tattered flowers, so I turned my attention elsewhere. The combination of rushes and reflections in this small pond in the Alpine Garden was photographed as a result.
Members of the rush family, Juncaceae, are found on every continent except Antarctica. However, because they tend to be associated with water, it is easy to explain their collective absence from the deserts of Africa, central Australia and Greenland. Not so easy to explain is the fact that they are found in most tropical areas except the Amazon rainforest and Madagascar. I imagine there is a biogeographical hypothesis for the lack of Juncaceae on Madagascar, but I personally can't come up with a plausible bit of speculation regarding the Amazon.
Despite Juncaceae's wide distribution, two related plant families have an even broader distribution, encompassing all areas of the world except for Antarctica and the frozen desert of Greenland: Poaceae and Cyperaceae (the grasses and the sedges).
To a casual observer, sedges, grasses and rushes all resemble each other (long, thin leaves & small flowers), so you might be asking yourself “How do I tell them apart?” A mnemonic taught to most botany students gives some hints: “sedges have edges, and rushes are round, but grasses have nodes from their tips to the ground”. For an explanation, visit University of California Museum of Paleontology's page on Glumiflorae.
I guess a couple of possibilities as to why the Amazon rainforest lacks any Juncus spp. could be: 1. this particular plant may require a certain level of readily available Nitrogen and the soils of the Amazon Basin are unable to store significant amounts (or other nutrients) as NO3 is constantly leached through the action of water; 2. another possibility could be the inability for certain types of mycorrhiza to inoculate the soil, an association (arbuscular type) that is frequent in other Central/South American habitats where Juncus spp. exist. and a feature of most plants in mature tropical forests- perhaps this is geologic or more alarmingly, an indication of steadily increasing levels of deforestation disturbance which destroys mycorrhizal communities quite easily.
Exquisite image - started my day with a zing. Thanks!
That has to be Photo Of The Year. Thanks Daniel.
oooo - Daniel, Marjorie stole my comment.'-D
Your photo is exquisite! It's so serene, and the quiet colors only add to that sense. Wow! I agree with Sunny, too - Photo of the Year. ****
Actually, one grass species does exist in Antarctica--and one member of the pink family as well!
http://www.antarctica.ac.uk/About_Antarctica/Wildlife/Plants/index.html
Great site; I've enjoyed it very much since I discovered it a year ago!
Amazing photo! I guess I am not the only one to think so!
Thank you for the kind words, all.
Dan – thanks for the reminder about that. Your note prompted me to remember I mentioned that Antarctic grass somewhere on BPotD over a year ago. Too bad the distribution map for Poaceae on the Angiosperm Phylogeny Group web site doesn't quite match – I should have remembered, in any case.
uau!!!
Wonderful photo. Really special!
What a fantastic picture. Made my day too!
when this came on the screen...i went "whew"...what a great pic !!!
my message is overdue and more of the same, but I just HAD to say ... a really beautiful photo, the color combination alone is wonderful!