Tue, 9 Oct 2001 11:54:35 -0500
From: Dennis K Demcheck <ddemchec@USGS.GOV>
Reply-To: BB for Hummingbirds and Gardening for them in the Southeast
<HUMNET-L@listserv.lsu.edu>
To: HUMNET-L@listserv.lsu.edu
Subject: [HUMNET-L] Observations of Salvia madrensis

While doing some routine percent sugar sampling of the salvias in my
backyard (tracking those pesky variations) yesterday I made some
observations that I think are interesting.

The salvia garden has S. madrensis, S. guaranitica (3 varieties), S.
leucantha, and S. coccinea. Currently the garden is swarming with European
honeybees and Carpenter bees. I was being lazy on my day off and didn't
start sampling until about 11 am. As expected, the various salvias were
seriously depleted of nectar and I was having trouble getting enough for a
reading. Then I sampled the S. madrensis. They were packed with nectar,
and using the Tindle method, by backlighting the bloom the nectar could be
easily seen. The was more than enough nectar that I could get
refractometer readings from single blooms. Results from three readings:
Greater than 32%, greater than 32%, and greater than 32%. Yep. That's a
lot of available energy.

That really got my attention. Then I noticed that the bees were not going
to the madrensis. This is in a small 10X10 ft plot, with the salvias
intermixed. I said to myself, "This is weird." I watched the bees and
noticed that the big glossy-black Carpenter bees would alight on a
guaranitica bloom and insert their mouthparts between the corolla and
calyx. I then looked around and realized that all the non-madrensis blooms
had fine slits cut into the bloom right where the calyx meets the corolla.
No wonder they were dry or nearly so. None of the madrensis blooms were
cut in this manner.
I inspected the madrensis blooms more closely. Betty Clebsch, in her
A Book of Salvias (p. 119) writes about "...calyses that are aromatic and
sticky with glands." That's certainly true, but it doesn't seem to be so
sticky that it would deter something as relatively large as a Carpenteree. But it does.
While marveling about how differently these salvias were apparently
handling the presence of bees, a Ruby-throated hummingbird buzzed in and
drank from the madrensis about 2 feet from my face. Was I witnessing
co-evolution in action? I may not be sure what I was observing, but I
think Mother Nature was hammering a lesson into my head. I'm just not sure
what the lesson is.

Dennis Demcheck
Baton Rouge

===================================================

Date: Wed, 10 Oct 2001 17:47:44 -0500
From: Van Remsen <najames@unix1.sncc.lsu.edu>
To: HUMNET-L@listserv.lsu.edu
Subject: Re: [HUMNET-L] Observations of Salvia madrensis

Dennis/HUMNET: very interesting observations on S. madrensis, which has
always been one of my best flowers for western hummers. That high sugar
concentration you found may explain why hummers like it, perhaps combined
with Dickson's hypothesis on height-above-ground -- this is one of the
tallest salvias. I'd noticed that sticky stuff around the flowers that
you mentioned -- in fact, it often accumulates bits of debris, but it's
not sticky enough to completely deter my honeybees, unfortunately. Lets
hope your bees don't develop the nasty habits that mine have.

Adding to the positive points for S. madrensis is that it spreads all by
itself and it is very root-hardy here in Zone 8b. On the negative side,
most years it is afflicted by a small green caterpillar that eats the
flowers before they can open; it's also one of those plants that turns
black instantly at 32 degrees -- very wimpy foliage.

################################

Van Remsen,
LSU Museum of Natural Science,
najames@unix1..sncc.lsu.edu