ARUM APULUM

Species

PROTOLOGUE: Arum apulum , published in The Genus Arum (Kew Magazine Monograph): 104 (1993).

Arum apulum (Carano) Boyce, stat. nov. Arum nigrum Schott var. apulum Carano in Ann. Bot. 20(3): 584, t.17 (1934). Type: Italy, Bari, Gioia de Colle (holotype FI! isotype NAP). [Arum apulum (Carano) Bedalov in Bot. Helvet. 94: 385 (1984), comb. ined.] Comparison of Arum apulum with Arum orientale reveals that the unstained ovary apices, spathe with a high proportion of green along the margins and apex and the more southerly distribution of Arum apulum easily distinguish them. The differences between Arum apulum and Arum nigrum include the former's slender, far more numerous sterile flowers, much more slender spadix-appendix and paler spathe-limb colour.

SYNONYMS:

HOMOTYPIC SYNONYMS: Arum nigrum var. apulum Carano

DISTRIBUTION: SE. Italy (Gioia del Colle): Italy.

SPECIES DESCRIPTION:

Tuberous herb sprouting in late autumn from a discoid, vertically orientated tuber 4—6 cm across, 2—2.5 cm thick. Petiole terete, 12-34 cm long, 2-4.5 mm wide, dull green, stained with purple for c. 1/4 of its length. Leaf-blade hastate-sagittate, apex subacute, 8-16 cm long, 5—13 cm wide, deep green

INFLORESCENCE:

Inflorescence smelling very weakly of horse-dung and urine. Peduncle much shorter than the leaves, terete, 4-11 cm long, 3-5 mm wide, dull purple. Spathe 12-18 cm long; spathe-tube oblong-ellipsoid, 4—4.5 cm long, 1.5—2 cm wide, constricted apically, exterior mid-green, interior purple, paler towards the apex; spathe-limb oblong-lanceolate, 7-10.5 cm long, 3-5 cm wide, erect, acuminate, externally purplish green, green towards the margin, internally dark purple, the margin and apex mid-green. Spadix c. 1/3 as long as the spathe-limb, 4—6 cm in total length; appendix slender-clavate, longstipitate, 3—4 cm long, 3—5 mm wide, purple, stipe reddish purple. Staminodes in 3 or 4 whorls, forming a zone 3-4 mm long; bristles filiform, flexuous, 3-3.5 mm long, purplish cream; bases compressed-conic, verrucate, cream. Interstices: upper 3.5—4 mm long, longitudinally ridged, cream; lower 2-3 mm long, + smooth, cream. Staminate flowers in an oblong zone 2.5—3 mm long, 5—5.5 mm wide; anthers purple and connectives cream. Pistillodes in 1 or 2 whorls forming a zone 1.5—2 mm long; bristles filiform, flexuous, 3—7 mm long, purplish cream; bases bulbiform, verrucate, cream. Pistillate flowers in an oblong-cylindric cluster 7-11 mm long, 5-7 mm wide; ovaries oblong,: truncate apically, 2.53.5 mm long, pale lime-green; stigma purple. Fruiting spike oblong-cylindric, 3-5 cm long, 2—2.5 cm wide; berries oblong-pyriform, 5—9 mm long, 4—6 mm wide

ECOLOGY:

300—400 m; altitude: 300-400 m

DISTRIBUTION MAPS:

ETYMOLOGY:

Of Apulia (Puglia), south-eastern Italy.

NOTES:

1. It belongs with Arum cyrenaicum, Arum nigrum and Arum purpureospathum to a dung-scented group whose appendix odor is built on three unsaturated hydrocarbons.⁴

REFERENCES:

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

2. The Genus Arum (Kew Magazine Monograph): 104 (1993) — protologue.

3. iNaturalist: Arum apulum

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. 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.

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

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

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

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