The Diary of The Botanic Gardens at Kona Kai: April 2015

I recently attended an Earth Day event at the Crocodile Lake National Wildlife Refuge on north Key Largo. A group of about 20 volunteers including members of FAVOR (Friends And Volunteers Of Refuges) and local state park and wildlife refuge staff and volunteers, came out to plant native trees. We were at an overgrown, cold-war era Nike Missile Site that the tropical hardwood hammock is reclaiming. Due to the sensitive environment, this area is off-limits to the public unless there is a special project. The Wildlife Refuge was originally created to protect the federally endangered American crocodile but there are several other endangered species that fall under the protection of this "umbrella" species.

We planted over 90 Torchwood (Amyris elemifera; Rutaceae) trees which are the host plant for the federally endangered Schaus swallowtail butterfly (Heraclides aristodemus ponceanus). The Bahamian and Giant swallowtail butterflies also lay eggs on this plant. The caterpillars of all three species feed on the young leaves of torchwood. Besides being important for insects, this tree provides interesting and important uses for humans, as well. Torchwood is in the citrus family and has edible fruit and some medicinal oils. The common name comes from its use as a torch; the young green branches are full of volatile oils which are easy to ignite.

The native plant nursery for Dagny Johnson Botanical State Park grew the plants from seed and nurtured them along for several months. Apparently, torchwood is very difficult to grow from seed and many of the seedlings did not make it; we were lucky to have as many as we did. The soil in the planting area was coral limestone rock with little topsoil. Torchwood likes to grow on open edges so holes were dug along the edge of a dirt access road, out in the full sun. The native soil in the planting holes was mixed with a small amount of potting soil and a few fertilizer pellets to give the seedlings a fighting chance in this harsh environment. At least three inches of mulch in a three foot diameter was laid down around the seedlings and two gallons of water were given to each plant to help them establish. Refuge staff will continue watering the plants periodically.

Many of our local butterfly experts who perform annual surveys for the Schaus swallowtail joined the group. Historically, the Schaus swallowtail butterfly was found throughout the southern tip of Florida in Dade and Monroe counties, extending south to lower Matecumbe Key. Now its range is restricted to several small islands in Biscayne National Park and north Key Largo, with less than 100 butterflies counted per year during annual surveys. Scientists were worried that the Key Largo population had blinked out, after not seeing any butterflies for several years in a row. Luckily, two Schaus swallowtails were observed flying on Key Largo last spring. One individual male butterfly was observed flitting around volunteers' heads for over 10 minutes! Even though he was observed "on the wing" they were able to take several hundred photos and got a clear shot for a positive ID. In June 2014, several hundred hand-reared Schaus swallowtail butterfly larvae and a few adults and pupae were released on nearby Elliott Key in Biscayne National Park, we are hoping that some will end up flying down here and re-populating the hammocks on Key Largo. Hopefully our torchwood trees will thrive and become a flaming beacon to the Schaus swallowtail butterflies.

An old launching shelter being taken over by a strangler fig.

Refuge superintendent, Jeremy Dixon, with his righthand man/son, Connor, describing the day’s activities (foreground) with Dagny Johnson Botanical State Park Nursery manager and torchwood grower, Jackie DeGaynor (back middle) looking on.

A torchwood seedling awaits its new home (which doesn’t look too inviting with all that rock). We were lucky to have pre-dug planting holes waiting for us!