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.