Sunday, August 24, 2014

Hunting and Fishing (part 1)

Some friends in the world of Cakile (sea rocket, the annual beach plant I researched for my Master's) want to know the extent of the spread of two closely related species (C. edentula and C. maritima) along the west coast of North America, including California, Oregon, and Alaska.

Sea rocket originated in the Middle East a long, long time ago, eventually migrating on the ocean currents across the Atlantic to North America. The seeds of this plant are quite remarkable. The seed is about the size of a grain of rice, encapsulated in a very buoyant, fleshy, salt water-resistant fruit that looks kind of like strings of shiny little plastic green beads arranged along a stalk. Because of this floaty quality, the seed has hitch-hiked around the world to seek its fortune as a kind of biological stowaway in the ballast water of ships. After a long ocean voyage, it loves nothing better than to germinate on the bare sand a few feet from the surf. Once established, it grows quickly into a large, sprawling weed, topped with unremarkable little purple flowers.  The non-showy flowers can be either self-pollinated or get somebody else's pollen from a visiting bee or fly. The plant puts most of its energy into developing those shiny little beads to perfection. A good half-meter sized Cakile (or "Cakilezilla" as I like to call them) can contain hundreds of fruits, and all this weight eventually results in the plant collapsing upon the sand, which is perfect, as you will see. The fruits consist of two very cleverly designed segments: the segment closest to the branch end is usually cross-pollinated, while the segment on the very tip is usually self-pollinated. Once the seeds have ripened, the fruits at the tip can detach and float away, while those on the branch end stay put on the mother plant. Alas, Cakile is an annual, so Mom always dies in the end, but her attached children--half siblings for the most part---overwinter in the sand to germinate the following spring.

Two years ago, I'd spotted a single specimen of American sea rocket (Cakile edentula) on the little beach behind Two Sisters Bakery in Homer, Alaska. I told my friends I'd try to make it down there this summer. As luck would have it this year was good timing, and Joanne, who makes her living among humans as a nurse practitioner, was game to accompany me for a couple of days of exotic plant sleuthing.

I honestly didn't think we'd find any.  I'd decided on Homer Spit, a 4.5 mile stretch of sand that sticks out from the southern end of the Kenai Peninsula like a long, skinny finger into Kachemak Bay.  I chose a half-mile transect along the beach beginning at the RV park near the tip heading west toward the bright red wooden barn housing Lucky Pierre Charters. From my past experience, sea-rocket is usually found among people and their boats, and as we started out, we found lots of things that resembled sea-rocket: sea purselane (Honckenya peploides), seabeach groundsel (Senecio pseudoarnica), seashore saltbush (Atriplex drymarioides), and oysterleaf (Mertensia maritima) among others. Then Joanne called me over: she'd spotted it: Cakile edentula. The good folks of the West Coast Cakile Project had provided a great visual guide of both species that we'd printed for reference, and Joanne, who has no botanical training outside of gardening, was a natural. Once we saw the first one, we found others rather few and far between. We came to the end of the transect with just 24 plants, and then in the shade of Lucky Pierre's we found more than three times that many: some were tiny little things with one or two fruits, most were medium-sized, and some were big honking Cakilezillas loaded with beads.  Although European sea rocket (Cakile maritima) has been documented in Alaska, we did not find a single one in our beach walk.

But this was just Part One of our excellent adventure...

our sampling map

Homer Spit looking East toward Seldovia

Sea rocket growing among rocks by the sea

C. edentula fruits resemble shiny green beads

me with a Cakilezilla

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