ARUM PURPUREOSPATHUM
PROTOLOGUE: Arum purpureospathum , published in Aroideana 10: 8 (1987).
Arum purpureospathum Boyce sp. nov. Arum maculato similis, sed appendice spadicis spathaque toto atropurpureo, foliis autumno crescens maioris hastatis non sagittatis differt. TYPE: Agia Roumeli in field beside church. Growing in stony terra rossa and short grass, 6 April 1985. In Herb. Kew.
DISTRIBUTION: SW. Kriti: Kriti.
SPECIES DESCRIPTION:
Tuberous herb sprouting in early to mid-autumn from a discoid, vertical tuber 4–7 cm across, 2–3 cm thick. Petiole D-shaped in cross-section, 12–20 cm long, 3–5 mm wide, deep green longitudinally streaked with purple, the basal ⅓ stained with the same colour. Leaf-blade sagittate-hastate, apex acute to rounded, 14–22 cm long, 11–17 cm wide, light to mid-green, glossy.
INFLORESCENCE:
Inflorescence smelling weakly of horse-dung. Peduncle shorter than the leaves, terete, 12–15 cm long, 5–6 mm wide, upper ½ mid-green with purple streaks, lower half purple. Spathe 23–30 cm long; spathe-tube oblong-cylindric, 5–7 cm long, 1.75–2.5 cm wide, tapering and constricted apically, exterior mid-green longitudinally striped with purple, and stained with purple above, interior uniformly deep purple; spathe-limb broadly lanceolate, 18–23 cm long, 5–9 cm wide, erect apart from the apical 3–4 cm which droops forward, long-acuminate, externally deep green basally, remainder deep purple, shiny, internally mid-purple or dull to deep bright purple, ± lustrous, rarely somewhat matt. Spadix ⅓–½ as long as the spathe-limb, 6–12.5 cm in total length; appendix clavate-cylindric, long-stipitate, obtuse, 3–5 cm long, 2.5–5 mm wide, black-purple. Staminodes in 3 whorls forming a zone 3–8 mm long; bristles filiform, flexuous, 6–11 mm long, pale mauve; bases conic, verrucate, deep purple, occasionally paler. Interstices: upper 3–6 mm long, longitudinally ridged, black-purple to cream; lower 1–3 mm long, cream, with scattered rudimentary and ± fully developed staminodes. Staminate flowers in a quadratic zone 4–7 mm long, 5–9 mm wide; anthers black-purple, connectives whitish cream. Pistillodes in c. 3 whorls forming a zone 3–5 mm long; bristles filiform, flexuous, 9–10 mm long, pale mauve; bases elongate-pyriform, smooth, black-purple. Pistillate flowers in a cylindric cluster 15–20 mm long, 7–10 mm wide; ovaries barrel-shaped, 2.5–3.5 mm long, pale green with a cream apex; stigma cream tinged with brown. Fruiting spike oblong-cylindric, 6.5–8 cm long, 2.5–3 cm wide; berries pyriform 6–11 mm long, 5–6 mm wide.
ECOLOGY:
In short grass and among large stones, rarely on bare rocky hillsides or in garrigue; altitude: 0-100 m
DISTRIBUTION MAPS:
ETYMOLOGY:
Latin purpureus, “purple”, with spatha: the spathe is wholly dark purple, inside and out.
NOTES:
1. Its pollinator has not been recorded. Its trap micro-anatomy sits within the midge cluster, a morphological prediction only.¹²
2. It belongs with Arum apulum, Arum cyrenaicum and Arum nigrum to a group of dung-scented species that share one appendix odor profile, dominated by three unsaturated hydrocarbons.¹²
REFERENCES:
1. Plants of the World Online, Royal Botanic Gardens, Kew — Arum purpureospathum
2. Aroideana 10: 8 (1987) — protologue.
3. iNaturalist: Arum purpureospathum
4. Boyce, P.C. 1993. The Genus Arum: a Kew Magazine Monograph. Royal Botanic Gardens, Kew.
5. Boyce, P.C. 2006. Arum – a decade of change. Aroideana 29: 132–137.
9. Gibernau et al 2004. Floral odor of Arum italicum.
10. Delpino 1874. Ulteriori osservazioni e considerazioni.
11. Gasparrini 1851. Enveloppe florale dans l'arum.
Additional photos by David Scherberich