ARUM IDAEUM

Species

PROTOLOGUE: Arum idaeum , published in Bulletin de la Société Botanique de France 63: 11 (1916 publ. 1917). The protologue is reproduced below.

DISTRIBUTION: Kriti: Kriti.

SPECIES DESCRIPTION:

Tuberous herb sprouting in early winter from a discoid, horizontally orientated tuber 3.5—5 cm across, 1.5—2.5 cm thick. Petiole terete, 8-21 cm long, 6-7 mm wide, dark green, heavily stained with purple, especially at the base. Leaf-blade oblong-sagittate, apex bluntly acute, 10—22.5 cm long, 8-17 cm wide, deep green.

INFLORESCENCE:

Inflorescence unscented. Peduncle shorter than to just equalling the leaves, terete, 5–17 cm long, 3.5–5 mm wide, deep green, heavily stained with deep purple, the staining ending abruptly at the base of the spathe-tube. Spathe 7.5–11 cm long; spathe-tube broadly oblong-cylindric, 2.5–4 cm long, 1.5–2.5 cm wide, slightly constricted apically, exterior pale lime-green with very faint purple marbling basally, margin whitish green, interior whitish green; spathe-limb narrowly elliptic to lanceolate, 5–9 cm long, 2.5–3.5 cm wide, erect, cucullate, acute, externally white tinged with pale green, internally white with numerous scattered translucent patches, margin with a very narrow purple border. Spadix c. ¾ as long as the spathe-limb, 7.5–9.5 cm in total length; appendix fusiform-cylindric, laterally compressed, shortly and stoutly stipitate, 5.5–7 cm long, 6–9 mm wide, dull deep purple with a few lilac patches, rarely dirty yellow with diffuse pale purple marbling, stipe encircled by a narrow lilac band basally, rarely dirty cream. Staminodes and pistillodes absent, but very rarely a few vestigial purple staminodes may be present. Interstices absent. Staminate flowers in a conical zone 7–9 mm long, 6–7 mm wide, contiguous with the pistillate flowers; anthers and connectives deep purple. Pistillate flowers in an oblong-cylindric cluster 14–17 mm long, 9–12 mm wide; ovaries oblong, rounded apically, lime-green; stigma white. Fruiting spike oblong-cylindric, 3.5–6 cm long, 2–2.5 cm wide; berries oblong-pyriform, 5–9 mm long, 3.5–5 mm wide.

ECOLOGY:

Soil pockets between boulders, scree, stony mountain meadows, often close to the snow-line; altitude: 600-1750 m

DISTRIBUTION MAPS:

ETYMOLOGY:

Of Mount Ida (Psiloritis), the Cretan massif; the species grows in soil pockets and scree close to the snow-line.

NOTES:

1. One of only two bee-pollinated species in the genus, sharing Halictidae with its sister Arum creticum.¹¹

2. Its trap has been abandoned altogether. It is the only species in the genus with no papillae anywhere — the spathe blade is lined with plain tabular cells — and it has neither lacunae nor elongated sterile flowers. Even the appendix, papillate in every other species examined, is smooth. In the ordination of trap micro-anatomy the two bee species stand further from every other species than any other pair.¹¹

3. A loss of dichogamy leaving the species capable of selfing has been reported, but only as unpublished observation, and it has never been tested.¹¹

REFERENCES:

1. Plants of the World Online, Royal Botanic Gardens, Kew — Arum idaeum

2. Bulletin de la Société Botanique de France 63: 11 (1916 publ. 1917) — protologue.

3. Boyce, P.C. 1993. The Genus Arum: a Kew Magazine Monograph. Royal Botanic Gardens, Kew.

4. Boyce, P.C. 2006. Arum – a decade of change. Aroideana 29: 132–137.

5. Chartier et al. 2013. Geographical variations of odour and pollinators, and test for local adaptation by reciprocal transplant of two European Arum species. Functional Ecology.

6. Diaz et al. 2006. The effectiveness of some mechanisms of reproductive isolation in Arum maculatum and A. italicum (Araceae). Botanical Journal of the Linnean Society.

7. Albre et al. 2003. Pollination ecology of Arum italicum (Araceae). Botanical Journal of the Linnean Society.

8. Delpino 1874. Ulteriori osservazioni e considerazioni.

9. 2006. Studies on the Genus Arum (Araceae).

10. Gibernau et al 2003. Arum Pollen longevity & viability.