05 November 2005

Maui Pictures 1: Haleakala Silverswords

Now that I've had a few days to get caught up on work, I've finally got a little time to sit down and go through some of the pictures from my Maui trip. I'm going to post some of the more interesting ones here from time to time.

The first picture, below, was taken on 30 October 2005, on the Sliding Sands Trail inside Haleakala Caldera. Haleakala Caldera really cannot be adequately described. It is an almost completely alien place, a landscape that looks more appropriate to a Sci Fi movie than to anything on Earth.

The plants in this picture are Haleakala Silverswords (Argyroxiphium sandwicense ssp macroencephalum). This subspecies is only found high on the slopes of Haleakala, and within Haleakala Caldera. It is federally listed as an endangered species.

The plants in the lower left of the photo show the normal form of the plant. The silvery appearance of the leaves is due to fine, reflective hair-like projections that cover the leaves. These reflect light, protecting the plants from the high intensity solar radiation that they receive, growing as they do at high altitudes and tropical latitudes. The individual leaves are small and narrow, minimizing water loss in this dry, windy environment.

The Haleakala Silversword has what is known as a monocarpic life history. This means that the plants grow for several years (up to 20 in the case of the silversword) before producing a single flowering head. After flowering once, the plant dies. Several of the plants in this picture have recently flowered, and are dead or dying.

A. sandwicense is part of a group of endemic Hawaiian plants known as the Silversword Alliance. This group consists of the genera Argyroxiphium, Wilkesia, and Dubautia, all of which are the descendents of a single species that arrived in the Hawaiian Islands, probably from North America, millions of years ago.

More information on this species can be found at Wikipedia.
Post a Comment