Border Rush

12 Dec


(If you wound up at Treasure Coast “Natives” in an article on border rush, out of interest in immigration policy, wrong blog)

Juncus marginatus and kindred species


Some plant families don’t get the attention they deserve. Yesterday marked the end of my fall term botanical field trip class, and to cap it off we circumnavigated the pond by the Palm Beach State College plant nursery.  A few steps around the shore revealed three species of rushes, about half the species hereabouts.  We saw border rush, needle pod rush, and the one I like to say: big head rush.  Reminds me of Rush Limbaugh:  Yakaloticus megacephalus var. tiltrightiana.

Rushes are the Juncaceae (junk-ACE-ee-ee), a relatively small family of maybe just 300 species around the world, more prolific in cooler climates than in the tropics.  Florida has a big handful, mostly in the genus Juncus plus a toehold by the genus Luzula.

Big Head Rush

Big Head Rush

Rushes, sedges, and grasses have long recognized as close allies.  I think it’s fair to portray the traditional view as sedges and grasses married, with the rushes a more primitive cousin.  However, surprise, DNA shows the rushes and the sedges to be the natural couple, and the grasses as the third wheel.

Big differences in the little flowers.  The rushes of the only ones of the trio to have flowers with sepals and petals.  (Some sedges have lame excuses for these.)  And further, unlike the single-seed grain-type fruits (achenes) of grasses and sedges, rushes uniquely have a woody capsule able to split open and release multiple seeds, often in vast numbers.

Border Rush pods (by John Bradford)

Border Rush pods (by John Bradford)

Wind is the pollinator for all three families, with exceptions.  As one insect-pollinated exception, Florida native plant enthusiasts enjoy the pretty painted sedges Rhynchospora colorata and relatives.  When I was younger these went by the name Dichromena, which I just like.  Unlike most sedges, the painted sedges have leaves beneath the tiny flowers either partially or completely white, mimicking petals and thus attracting 6-legged pollinators.

Pained sedge in Florida with white bracts around the smaller flowers

Painted sedge in Florida with white bracts around the smaller flowers

Why would I bother contaminating a post on poor under-valued rushes with insect-pollinated sedges?  Answer: rushes do essentially the same thing (with slightly different organs putting on the white), in Asia.  The insect-pollinated Juncus allioides looks much like our local painted sedges.  Botanists studying that Asian species suspect insect-pollination in rushes to be more fundamental and widespread than usually perceived.  And here’s why.  We know already how rushes have sepals and petals.  The purposes of these organs is to attract insects, so why do wind-pollinated rushes have them?  (Why do occasional human babies have tails?)   In rushes the petals are tiny and ineffective for as bug-lures.  They must be left over from insect-pollinated ancestors with bigger showier petals.  In other words, rush petals and human tails are vestigial.

Juncus allioides, insect-pollinated and white-topped, in Asia.  Photo by Susan Kelley, from Flora north america.

Juncus allioides, insect-pollinated and white-topped, in Asia. Photo by Susan Kelley, from Flora North America.

And there’s more:  In the rushes the pollen grains cling together in clumps of four known as tetrads.  This makes sense in an insect-pollinated flower where one Fed-Bug delivery drops off four pollen grains, but tetrads are rare in wind-pollinated flowers where lightweight, separate grains are obviously optimal.  Again, tetrads apparently vestigial.  So let’s all keep our eyes open for more insect pollination in rushes.

Weirdness Alert!  Stop and think about all that for a second, Juncus allioides shows doubly flip-flopped evolution.  Start with an insect-pollinated ancestor great granddaddy rush, and turn it wind-pollinated like most modern rushes, here’s flip-flop #1.  Then have a species go back to insect pollination, there’s the flop.

Border Rush in flower (by JB)

Border Rush in flower (by JB)

Speaking of oddball reproduction, many plants sprout among their flowers baby plantlets called bulbils.  (Pups in garden parlance.)  These clones of the parent plant back up or even replace the sexual flowers.  Rushes occasionally make bulbils.  As an extreme for instance, Juncus pelocarpus has a southern variant formerly called Juncus abortivus, presumably because it’s flowers abort to make way for bulbils.  Our own border rush seems to sport bulbils, although it might be a good idea to do dissect a few to see if the emerging babies are bulbils or, alternatively, seeds germinating inside the fruit while still in the mama plant.  I’m betting on bulbils.

Border rush with apparent bulbils sprouting on the parent plant

Rushes have some human history.  Around the world they yield fibers (Juncus textilis) used for cords, nets, basketry, and mats, including the beautiful tatami mats of Japan.

Apocalypse survivors may sleep on rush mats, catch fish with Juncus nets, and light their smelly hovels with rushlights.  Historically in Europe, especially the U.K., people of meager means—or the budget minded—made rushlights using soft rush, found in England, in Florida, and vastly far beyond.  (In fact the same species is the one in the Japanese t-mats.)  To make a rushlight you harvest soft rush, peel off most of the skin, dry it, soak it in kitchen grease, and fire up an inexpensive candle.  These were mounted in rushlight holders, which now are collectors items and museum pieces.  Soft rush is abundant in the U.K., and I’m hoping our British blog friend Mary Hart is reading this and may perhaps even comment.  Not too many species shared between Palm Beach County and Worcester (go Wolves!) in Worcestershire.

Rushlight (see link in text)

Rushlight (see link in text)

(Here is a great link to rushlights, and the source of the photo I stole.)

This post is getting too long so we better rush to wrap it up, and to help with that here is Aesop with rushlight wisdom, oh so apropos to us blog writers as we self-proclaim our value as unvetted, unedited, uncorrected un-competitive luminaries:

 A Rushlight that had grown fat and saucy with too much grease, boasted one evening before a large company that it shone brighter than sun, moon and all the stars.  At that moment, a puff of wind came and blew it out.  One who lighted it again said, “Shine on, friend Rushlight, and hold your tongue; the lights of heaven are never blown out.




Who took today’s pictures?

For some photos, I do not recall who took what.   They are from the catacombs.   If it is sharp and vibrant, probably John.  Out of focus, me.

For the gardeners:

Big Twister

Not rushes:

Bulrush (Schoenplectus, and other sedges, and Typha)

CatTails (Typha species)

Spikerush (Eleocharis species, sedges)

Scouring Rush (Equisetum species, “Fern Allies”)

Flowering Rush (Butomus umbellatus)

Species you might find in our haunts, quickie notes:

(I am not interested in taxonomic/geographic/nomenclatural quibbles.  These topics are not of much interest here and now.  Quibblers:  git yer own pretentious dang blog):

Juncus effusus.  Soft Rush.  Worldwide. Looks substantially different from the other local Juncus species; resembles a Bulrush at a glance

Juncus marginatus.  Border Rush.  The most abundant species locally, flower heads small, irregular, and messy, not globose.  Leaves not septate.

Juncus megacephalus.  Big Head Rush.  Common, flowers heads big and globose.  Leaves septate.

Juncus paludosus.  A recently named species restricted to Florida, resembling J. polycephalus.

Juncus polycephalus.  Many Head Rush.  Many small globose heads, marginal geographically to us

Juncus repens.  Often submersed, flat, different from the others.  A popular aquarium species.

Juncus scirpoides.  Needlepod Rush.  Common.  Flower heads half-globose, a little messy.  Leaves septate.

Needlepod Rush

Needlepod Rush


Posted by on December 12, 2014 in Border Rush



4 responses to “Border Rush

  1. Steve

    December 12, 2014 at 3:07 pm

    Me likes graminoid articles. Juncus marginatus (or what I affectionately call Junk Marge) breaks the rules of that little sing song chant “Sedges have edges, rushes are round, and grasses are hollow like a whole in the ground” as its leaves are flat, not round. That memory device is crud. I thought the talk show host species epitaph was phallocephalus? Great article George!

    • George Rogers

      December 12, 2014 at 7:56 pm

      The trouble with mnemonics is that they are just even more to memorize, although ULAAF for the components of blood plasma sticks for some perverse reason. I can’t mention the genus Phallocephaphalus in this family blog, but it seems to have a lot of species.

  2. theshrubqueen

    December 12, 2014 at 5:01 pm

    Great photos! I love the Curly Juncus – haven’t seen any around here..

  3. George Rogers

    December 12, 2014 at 7:57 pm

    How’d I know you’d like Curly Juncus…put it in just for your twisted aesthetics. It looks to me like a Spirulina from the health food store on steroids.


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