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Petrocosmea cryptica J.M.H.Shaw

Family: GESNERIACEAE

Publication: Plantsman n.s., 10(3): 178 (177-179; figs.). 2011 [Sep 2011]

Description

Petrocosmea cryptica is a perennial herbaceous plant of the family Gesneriaceae, the African violet family. It is remarkable for its neat, tightly imbricate, tile-like rosette structure of 3 cm ovate leaves, eventually producing offsets. The leaf surfaces have hairs arising from pustulate bases. This plants is wrongly labelled Petrocosmea rosettifolia or Petrocosmea G25KC00. The epithet cryptica refers to the identity of this species being hidden during the 10 or more years it has been in cultivation.

Leaves: Numerous (up to 160) borne on petioles to 3 cm long. Blade 25–40 mm long, 13–17 mm wide, elliptic, cuneate at base, apex acute, margin weakly thoothed towards apex. Upper surface sparsely covered by 3 mm long hairs arising from pustulate bases, midrib and veins visible as yellow green stripes, raised on lower surface. Leaf underside densely pubescent with 1.5 mm long hairs.

Inflorescences: One flowered (rarely few flowered). Peduncle 5–7 cm, finely pubescent, with linear bracts, 3–4 mm long. Pedicels 16–28 mm long, finely pubescent.

Flowers: Calyx segments 5, equal, lobes 30 mm long, 8 mm wide, inner surface glabrous

finely pubescent in the exterior. Corolla white with yellow in throat, tube to 3 mm long, upper lip 4.5–5mm long, gently indented to weakly 2-lobed, lower lip to 9 mm, 3-lobed, lobes rounded, 1.5–2 mm long. Filaments 3.5–4 mm long, curved, C-shaped, puberulent towards middle. Anthers 2, ovoid white. Pistil 8–8.5 mm long. Ovary c. 2.5mm long, densely covered

with long silvery hairs. Stigma club-shaped.

Blooming season: Flowering from autumn to winter, flowering can continue in to spring after a cold winter.

Similar species: Petrocosmea cryptica is similat to Petrocosmea rosettifolia, but the latter has broadly ovate or broadly elliptic leaves, and filaments glabrous, only 1 mm long (3-4 mm long in P. cryptica).

Origin and Habitat

China

Cultivation and Propagation

Petrocosmea offsets free. Once removed offsets are treated just like cutting until they form roots.

Theys may never need large pots.

Bibliography

Major references and further lectures

  1. Julian Shaw “A new species of Petrocosmea: Julian Shaw discovers that a gesneriad that has been in cultivation under the wrong name for more than 10 years is a new species” The Plantsman September 2011 pp 177-179. https://www.rhs.org.uk/about-the-rhs/publications/magazines/the-plantsman/2011-issues/september/Petrocosmea

  2. Drew, R (2002) “Sussex Show, October 6th. The Alpine Gardener” 70(1): 82–85

  3. Drew, R (2003) “Developing a collection of subalpine gesneriads”. The Alpine Gardener 71(3): 297–307

  4. Li, Z-Y & Wang, Y-Z (2005) “Plants of Gesneriaceae in China”. Henan Science and Technology Publishing House, China

  5. Middleton, DJ & Triboun, P (2010) “Two new species of Petrocosmea”. Thai Forest Bull., Bot. 38: 42–47

  6. Wang, W (1985) “The second revision of Petrocosmea”. Acta Bot.Yunnan. 7(1): 49–68

  7. Wang, W, Pan, K-Y, Li, Z-Y, Weitzman, AL & Skog, LE (1998) Petrocosmea. In: Flora of China Editorial Committee (eds) “Flora of China” Vol. 18. Science Press, Beijing, & Missouri Botanical Garden Press, St Louis

  8. Tim Tuttle “Culture of Petrocosmea: My Way” “As distributed to the National Capital Area Chapter of The Gesneriad Society in April 2009

Cultivars and forms (1)

Cultivars (1)