Plants colonising the new driveway

orchids

Our driveway was made when the house was built in the winter of 2008, as shown in the image. The sandy loam had been smoothed with a bobcat, a layer of road base gravel had been compacted on top, with some loose gravel spread over that.

From late winter 2010 to early autumn 2011, Phil noted the plants species that colonised Rubicon’s new driveway. Most observations were deliberate but not truly systematic. For at least one specimen of each species, we recorded a GPS waypoint, collected and/or photographed the plant, and identified any unfamiliar plants in the lab. With experience, we could identify many species in their infertile state, but some plants needed to flower if identification was not clear.

Species were counted as being in the drive if they were growing in gravel from the road edge to near the house. A small part of the driveway is relatively shady to the south of the house where water tends to pool temporarily after heavy rain, but most of the drive is open to plenty of sunshine and well drained.

Results

A total of 72 plant species were recorded growing in the gravel drive during the observation period. 31 of these species are introduced “weeds”, while the remaining 41 species are native to the site, but still considered to be weeds in the gravel!

orchids

 

Two species have not been seen elsewhere on the property: the introduced greater sandspurrey, Spergularia rubra (right), and the native rock stonecrop Crassula sieberiana subsp. sieberiana (below). Both of these species favour dry shallow soils.

 

orchids

 

67 of the species in the driveway had mostly grown from seed. Three species are assumed to have persisted from rootstock that was overtopped during driveway construction: Bossiaea cinerea (showy bossia), Lomandra longfolia (sagg) and Pteridium esculentum (bracken, the only fern in the list).

59 of the species are herbs, 12 are shrubs, and Eucalyptus amygdalina (black peppermint) is the only tree species to have germinated in the gravel. 28 species are annuals and the remaining 44 species are perennials.