ARUM GRATUM

Species

PROTOLOGUE: Arum gratum , published in Synopsis Aroidearum: 11 (1856). The protologue is reproduced below.

SYNONYMS:

HOMOTYPIC SYNONYMS: Arum orientale var. gratum (Schott) Engl.

HETEROTYPIC SYNONYMS: Arum melanopus Boiss.

DISTRIBUTION: W. Syria to N. Lebanon: Lebanon, Syria, Türkiye.

SPECIES DESCRIPTION:

Tuberous herb sprouting in early winter from a discoid, vertical tuber 3.4–5 cm across, 1.5–2.5 cm thick. Petiole terete, 17.5–25 (–30) cm long (up to 50 cm long according to Mouterde, 1966), 3–4.5 mm wide, deep green. Leaf-blade hastate-sagittate to oblong-hastate, apex subacute, 9–18 cm long, 7–12 cm wide, deep green, occasionally with jagged purple-black blotches.

INFLORESCENCE:

Inflorescence sweet-smelling. Peduncle very much shorter than the leaves, often absent above soil level, 0–2.5 cm long, 4–5 mm wide, pale green, longitudinally striped with reddish brown. Spathe 12–18.5 cm long; spathe-tube often partially buried, oblong-ventricose, 2–3.5 cm long, 1.5–2 cm wide, constricted apically, exterior off-white below (if buried) or pale green (if exposed), mid-green, stained with purple above, this colour intensifying towards the margins and apex, interior with a pale greenish white lower half and purple upper half; spathe-limb elliptic-ovate, 10–15 cm long, 5–6.5 cm wide, cucullate, acute to minutely acuminate, externally pale green flushed with pale purple, apex and median vein greenish, internally olive-green, ± flushed with pale purple, occasionally with jagged purple-black blotches. Spadix less than ⅓ as long as the spathe-limb, 5.5–6.5 cm in total length; appendix strongly clavate, stipitate, 4–4.5 cm long, 5–6 mm wide, reddish purple to greenish purple, stipe purple. Staminodes in c. 3 whorls forming a zone 1.5–2 mm long; bristles filiform, flexuous, 2.5–3.5 mm long, cream, tipped with purple; bases conic, smooth, cream. Interstices: upper 0.5–1 mm long, smooth, cream; lower ± absent. Staminate flowers in an oblong zone 4–5 mm long, 3.5–4 mm wide; anthers and connectives dull purple. Pistillodes in 1 whorl forming a zone 0.5–1 mm long; bristles aristate, stiff, 1.5–2 mm long, cream, minutely tipped with purple; bases globose, smooth, pale cream. Pistillate flowers in a globose-cylindric cluster 5–7 mm long; ovaries globose, 1.5–2 mm long, cream, barely stained with purple apically; stigma white. Fruiting spike cylindric, 3–4.5 cm long, 2–2.5 cm wide; berries pyriform, 7–10 mm long, 3.5–4.5 mm wide.

ECOLOGY:

Garigue, Cedrus woodland, deciduous woodland; altitude: 550-1500 m

DISTRIBUTION MAPS:

ETYMOLOGY:

Latin gratus, “pleasing, agreeable” — unusually for the genus, the inflorescence is sweet-smelling.

NOTES:

1. Its appendix is strongly clavate and sweetly scented, which sits oddly with its placement in subsection Dischroochiton, diagnosed as foetid or oily-smelling.⁴

2. Its chromosome number has never been established.⁴

REFERENCES:

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

2. Synopsis Aroidearum: 11 (1856) — protologue.

3. iNaturalist: Arum gratum

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. Corazza, C., & L.Cortopassi 2026. Arum brunneoviolaceum (Araceae), a new species from Central Turkey.

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