ARUM CYRENAICUM

Species

PROTOLOGUE: Arum cyrenaicum , published in Bulletin de la Société Botanique de Genève, sér. 2, 4: 159 (1912). The protologue is reproduced below.

DISTRIBUTION: SW. Kriti, NE. Libya: Kriti, Libya.

SPECIES DESCRIPTION:

Tuberous herb sprouting in early autumn from a discoid, vertical tuber 3.5–5 cm across, 2–2.5 cm thick. Petiole terete, 5.5–27 cm long, 3–6 mm wide, dark green with moderate purple staining. Leaf-blade broadly sagittate, apex obtuse to rather bluntly acute, 8.5–20 cm long, 4–12 cm wide, semi-glossy deep green.

INFLORESCENCE:

Inflorescence smelling slightly of horse-dung. Peduncle not exceeding the leaves, terete, 3–11 cm long, 5–7 mm wide, semi-glossy mid-green, longitudinally striped with lighter green and moderately stained with purple. Spathe 10.5–16 cm long; spathe-tube oblong-cylindric, 2.5–4 cm long, 2–2.5 cm wide, constricted apically, exterior pale green with a narrow dull purple margin, interior dark purple, fading to pale green basally and deepening to plum-purple apically; spathe-limb elliptic, 8.5–12 cm long, 4–5.5 cm wide, erect, the apex drooping forwards as the inflorescence ages, acuminate, externally greenish, flushed with purple towards the edges, interior pale rosy purple to dark purple, fading to pale purple towards the tube and apex, limb green at the tip. Spadix c. ½ as long as the spathe-limb, 7–9.5 cm in total length; appendix slender-clavate, long-stipitate, 3.5–6.5 cm long, 5–7 mm wide, deep purple with a slight olive-green tinge, stipe darker. Staminodes in 3 or 4 whorls, forming a zone 4–6 mm long; bristles filiform, flexuous, 6–7 mm long, cream, minutely tipped with purple; bases pyriform, slightly verrucate, cream, with the verrucae tipped with lilac-mauve. Interstices: upper 4–5 mm long, lower 3.5–4 mm long, both longitudinally ridged, cream. Staminate flowers in a cylindric zone 2.5–3 mm long, 7–8 mm wide; anthers and connectives deep yellow, thecae with dull purple staining along the edges. Pistillodes in 2 or 3 whorls forming a zone 5–6 mm long; bristles filiform, flexuous, 5–6 mm long, cream, minutely tipped with purple; bases pyriform, slightly verrucate, cream, the verrucae tipped with lilac-mauve. Pistillate flowers in an oblong-cylindric cluster 1–2 cm long, 6.5–7 mm wide; ovaries oblong, truncate apically, mid-cream; stigma cream. Fruiting spike short-cylindric, 2.5–4 cm long, 2–2.5 cm wide; berries pyriform, 4–9 mm long, 3–5 mm wide.

ECOLOGY:

Open scrub, amongst boulders, shady slopes; altitude: 20-350 m

DISTRIBUTION MAPS:

ETYMOLOGY:

Of Cyrenaica, the region of north-eastern Libya.

NOTES:

1. It flowers in April, and belongs with Arum apulum, Arum nigrum and Arum purpureospathum to the dung-scented group of subsection Dischroochiton.⁴

2. Peter Boyce advised a grower of seed-raised Arum cyrenaicum to keep the dormant pot dry but cool, without letting it bake, and in mid-July to empty the pot and replant the tubers about 2.5 cm deep, about 5 tubers to a 10 cm pot. Once new growth appeared, he advised growing the plants vigorously in good light and feeding with every other watering, and noted that it might even pay to move them up, without disturbing the tubers, into a 15 cm pot about halfway through the growing season. The next July the routine was to be repeated, probably at one tuber to an 8 cm pot and again moved up, without disturbing the tubers, into a 15 cm pot. Under this pot regime some of the more vigorous Arum cyrenaicum tubers would probably flower by the third year.¹²

REFERENCES:

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

2. Bulletin de la Société Botanique de Genève, sér. 2, 4: 159 (1912) — protologue.

3. iNaturalist: Arum cyrenaicum

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.

6. 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.

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

8. 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.

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

10. 2006. Studies on the Genus Arum (Araceae).

11. David Leedy 2014. Growing Arum — An Experiment in Fort Worth, Texas.