434 
junghuhniana J.Kost. This relatively small 
habitat space is periodically impacted by 
wildfires undoubtedly resulting in the markedly 
sharp rainforest margin. Adult plants of the 
Plectranthus are probably killed by these fires, 
but regenerate in situ either from seed or the 
fleshy rootstocks or ex situ by dispersal from 
adjacent plants within the vineforest canopy. 
Austrobaileya 9(3): 431-438 (2015) 
Notes : Plectranthus laetus was first collected 
in 2014 during a general botanical survey 
of Orchid Creek Station. The new species 
appears to be closely related to P. pulchellus 
(Forster 1994) that grows on sandstone 
substrates (cliff lines) adjacent to spring fed 
rainforests (evergreen notophyll/mesophyll 
vineforests) on the Olive River Reserve and 
from which it is disjunct by c. 70 km (Map 1). 
Map 1. Distribution of Plectranthus pulchellus • and P. 
conservation reserves and property boundaries. 
Plectranthus pulchellus differs from P. 
laetus mainly in the yellow sessile glands 
(versus orange) and the verticillasters with a 
greater number of flowers (12-16 versus 6-10), 
flowers with corollas that are light purple 
laetus ▲ on Cape York Peninsula, grey shaded areas are 
(versus blue-purple) and with smaller calyces. 
There are also other minor differences in the 
combinations of indumentum composition 
and cover on the foliage and floral parts; 
however, the speciation hypothesis is that the 
two are sister taxa. 
