Forster, Plectranthus laetus and P. ventosus 
435 
Etymology : The specific epithet is derived 
from the Latin word laetus (pleasant), an 
allusion to the appearance of this plant. 
Plectranthus ventosus RI.Forst., sp. nov. 
with affinity to P. parviflorus Willd. but 
differing in lacking a basal stem tuber (versus 
present), antrorse non-glandular trichomes 
on the foliage (versus retrorse) and obovate- 
rhomboid floral bracts (versus ovate to 
obovate). Typus: Queensland. Cook District: 
ex situ cultivation from Melville Peak, on the 
ridge between the headwaters of Sweetwater 
Creek and Temple Creek, Cape Melville 
National Park, 10 April 2015, H.B. Hines 
CM40 &C.J. Hoskin (holo: BRI). 
Perennial herb, stems erect to 15 cm high; 
foliage scentless when crushed, not clammy; 
non-glandular and glandular trichomes 
uncoloured, non-glandular trichomes without 
prominent raised bases, sessile glands 
absent. Roots fibrous, somewhat fleshy and 
thickened. Stems square, erect to straggling, 
fleshy, easily snapped, the lower parts up to 
8 mm diameter and not noticeably thickened, 
pink-purple to pink-green, upper parts with 
persistent indumentum, non-glandular 
trichomes sparse, antrorse, 4-6-celled up to 
1 mm long, glandular trichomes sparse, very 
short with little development of stalks. Leaves 
discolorous, petiolate; petioles 2-5 x 0.8-1 
mm, weakly channelled on top, non-glandular 
trichomes sparse, antrorse, 4-6-celled up to 
1 mm long, glandular trichomes ± stalkless; 
laminae lanceolate-ovate to ovate, fleshy, 
±flat to slightly keeled, 6-25 x 4-20 mm, 
crenate with 4-6 teeth up to 2 mm long 
on each margin, of similar length along 
margin, secondary teeth poorly developed; 
tip acute; base obtuse to rounded; upper 
surface medium-green and somewhat glossy, 
veins impressed, non-glandular trichomes 
sparse, antrorse, 4-6-celled up to 1 mm long, 
glandular trichomes absent; lower surface pale 
green, veins strongly raised, non-glandular 
trichomes sparse, antrorse, 4-6-celled up to 
1 mm long, glandular trichomes sparse and 
stalked to 0.4 mm long. Inflorescence up to 
100 mm long, usually single or with 1 or 2 side 
branches; axis square in cross-section, pink- 
purple, non-glandular trichomes occasional, 
weakly antrorse, 4-6-celled up to 0.2 mm 
long, glandular trichomes dense and minute 
(< 0.2 mm long); bracts obovate-rhomboid, 
strongly cupped, 0.9-1 x 0.8-1 mm, ecomose, 
margins somewhat irregularly crenate to 
crenulate due to slightly enlarged bases of 
trichomes, non-glandular trichomes sparse, 
antrorse, 2-4-celled up to 0.4 mm long, 
glandular trichomes occasional, ± sessile; 
verticillasters 6-10-flowered, 4-14 mm apart; 
pedicels 2-4.5 x c. 0.2 mm, non-glandular 
trichomes sparse, antrorse, 2-4-celled up to 
0.2 mm long, glandular trichomes ± sessile. 
Flower calyces 1.8-2 mm long, non-glandular 
trichomes sparse, antrorse, 2-4-celled up to 
0.2 mm long, glandular trichomes sparse and 
very short (< 0.2 mm long). Corolla either not 
opening (cleistogamous) or poorly formed, 
2.8-3 mm long, white, with some mauve 
edging; tube 1.8-2 mm long, ± straight, 
slightly inflated upwards, non-glandular and 
non-glandular trichomes absent; upper lobes 
suborbicular, inflexed, c. 0.5 x 0.5 mm, non- 
glandular trichomes scattered, antrorse, 
2-4-celled up to 0.2 mm long, glandular 
trichomes scattered < 0.1 mm long; lateral 
lobes rounded, c. 0.2 x 0.2 mm, glabrous; 
lower lobe oblong-ovate, 0.8-1 x 0.6-0.7 mm, 
non-glandular trichomes sparse, antrorse, 
2-4-celled up to 0.2 mm long, glandular 
trichomes absent; filaments filiform, 1.8-2 x 
c. 0.1 mm, lilac, fused for 0.8-1 mm from the 
base; anthers c. 0.2 x 0.1 mm; style filiform, 
c. 1.2 x 0.1 mm, cream, bifid for c. 0.2 mm. 
Fruit calyces 4.5-5 mm long; upper lobe 
broadly ovate, 1-1.2 x 1.6-1.8 mm; lateral 
lobes lanceolate, 1-1.2 x c. 0.8 mm; lower 
lobes lanceolate-falcate, 1.2-1.3 x 0.4-0.5 
mm. Nutlets ± circular in outline, compressed 
flattened globose, 0.7-0.8 mm wide, 0.4-0.5 
mm thick, brown, weakly verrucose. Figs. 2 
& 3. 
Distribution and habitat. Plectranthus 
ventosus is known so far from a single 
population at Cape Melville where it was 
collected on a ridge top ( c . 590 m altitude) 
growing amongst scattered large boulders 
in stunted rainforest immediately adjacent 
to an exposed boulder field. Substrate is 
coarse sandy loam derived from Cape 
Melville granite; however, the plants mainly 
