For many, the primary attraction of the genus Arum is the unique structure|
of the inflorescence coupled with its often rich coloration. Only
occasionally is the foliage mentioned as a further source of interest. Arum
pictum is one of the two notable exceptions, the other being A. italicumn
subsp. italicum. The leaves of A. pictum display a variety of colours,
depending on their stage of development. On first emerging they are deep,
shiny, metallic green, with the margins, and to a certain extent the blade,
tinged with purple. As the leaf expands the purple blade coloration fades
while the main and lateral veins become slightly paler. However, the margin
retains its coloration. As the season progresses the blade loses its sheen
but the veins continue to lighten until late spring, when they stand out as
a creamy white to silvery grey network. The late season colour of the leaves
of A. pictum is similar to that of many forms of A. italicum subsp. italicum
with silvery grey veining, although the leaf shape is very different. In
view of this similarity it is hardly surprising that these two plants have
been confused in the past despite their different growth habit and
Arum pictum produces inflorescences at the start of the growth period in
the autumn, a unique flowering pattern in the genus. In flower A. pictum
resembles A. nigrum, except that the peduncle is far shorter and the
spathe-limb has a much more pronounced sheen. Close inspection of the spadix
reveals only a single zone of sterile flowers, the staminodes, situated
above the staminate flowers. Furthermore the inflorescence of A. nigrum is
produced from the petiole-sheath of the terminal leaf at the completion of
the growth period, usually in April or May whereas in A. pictum the
inflorescence emerges just before, or with, the leaves at the start of the
growth period. Arum pictum was described by the younger Linnaeus; later
Schott (1855) transferred it to a new genus, Gymnomesium, justifying the
separation on the presence of a single, upper zone of sterile flowers
together with autumn flowering. However, Gymnomesium was not widely accepted
and many botanists still retained the species within Arum. Engler (1879) at
first treated Gymnomesium as a section within Arum but for Die Natürlichen
Pflanzenfamilien (1889) raised it to subgeneric rank. However, in Das
Pflanzenreich Engler (1920) once again treated Gymnomesium as a 'section',
assigning it an ambiguous rank (see Boyce, 1989). Following Engler (1889) I
have adopted subgeneric rank for this taxon in order to emphasize the
singularity of A. pictum.
Arum pictum is easily grown in a large pot, or in warm areas outdoors in a
sunny, well-drained position. Its hardiness has been doubted by many
growers, but a large clump of this species grown outdoors at the Cambridge
Botanic Garden has survived many winters with minimal damage.
Arum pictum L. fil. in Suppl. 410 (1782); Engler in A. & C. DC., Monog.
Phanerog. 2: 582 (1879); Hruby in Bull Soc. Bot Genéve 4: 158 (1912); Engler
in Engler, Das Pflanzenr. 73 (IV. 23F): 69-70 (1920). Type: Probably
described from cultivated material at Uppsala. (lectotype designated here:
Herb. Linn. 1079.9 [LINN !]). There is no material of A. pictum attributable
to either Linnaeus or Linnaeus filius in Uppsala. The single specimen in the
Linnean Herbarium, London, is in excellent condition and is the best
candidate for the lectotype.
A. balearicum Buc'hoz. Stated to have been published in Hist. Univ. 8: t.2
(1774) but the validation does not appear anywhere in this work and I have
been unable to trace any other place of publication. Type: The type would,
presumably, be the illustration cited above since Buc'hoz's herbarium is
not known to exist. In Leiden Herbarium there is an illustration
corresponding to the missing one.
Gymnomesium pictum (L. fil) Schott in Oesterr. Bot. Wochenbl. (1855),
Schott, Syn. Aroid. 8 (1856); Schott, Prodr. Syst. Aroid. 73 (1860). Type:
as for A. pictum L. fil.
Arum pictum L.fil lusus (sport) bispathaceum Engler in Engler, Das
Pflanzenr. 73 (IV. 23F): 72 (1920). Type: this plant was sent to the
editors of Gardener's Chronicle by Sprenger in 1904 (Gard. Chron. 36: 304
(1904). There is no material present in Berlin. Engler (1920) states 'von
Herrn Sprenger in kultur beobachtet', quotes Gardener's Chronicle
reference, but does nor refer to any specimens. From this I think it can be
assumed that the type never existed.
A. corsicum Loisel., Fl. Gall. (ed. 1) 2: 617 (1807). Type: not designated.
DESCRIPTION. Tuberous herb sprouting in early to mid-autumn from a discoid
vertical tuber 5-7 cm across, 2-2.5 cm thick. Petiole semiterete, 15-25 cm
long, 2-12 mm wide, pale to mid-green with slight purple staining basally,
with a conspicuous, open, triangular basal sheath. Leaf-blade ovate-cordate,
apex acute to obtuse, 9-25 cm long, 6-18 cm wide, shiny, deep metallic
green tinged with purple, especially along the margins when first expanded,
the veins paler, blade later becoming dull, deep green with a purple tinge
and creamy white to silvery grey, main and lateral veins, leaves very
occasionally plain green. Inflorescence appearing before or with the leaves,
smelling strongly of horse-dung. Peduncle sessile at ground level, or rarely
with up to 2 cm visible if growing in deep shade, terete, pale green. Spathe
11.5-21.5 cm long; spathe-tube oblong-cylindric, 2.5-5.5 cm long, 2.5-3 cm
wide, constricted at the apex, exterior off-white below ground, pale green
with scattered purple spots and staining above ground, interior dirty white
with purple staining along the margins; spathe-limb elliptic, 9-16 cm long,
4-6.5(-8) cm wide, slightly cucullate, shortly acuminate, externally
mid-green with heavy, deep purple staining, especially along the margins at
the apex, internally velvety deep purple, the apex occasionally mottled
mid-green. Spadix approximately 2/3 - 4/5 as long as spathe limb, 8-13 cm in
total length; appendix stoutly clavate cylindric, long-stipitate, 6-11 cm
long, 7-15 mm wide, deep purple-black with a satin sheen. Staminodes in 3
whorls forming a zone 3-5 mm long; bristles subulate, stiff, 3-4.5 mm long,
cream; bases slightly swollen, smooth, cream. Interstices: upper 2-3 mm
long, longitudinally ridged, off-white; lower 1-2 mm long, longitudinally
deeply sulcate, cream. Staminate flowers in an oblong to globose zone, 5-7
mm long and wide; anthers pale cream and connectives off-white. Pistillodes
absent or very rarely a few vestigial bases present above the pistillate
flowers. Pistillate flowers in a globose-cylindric cluster, 11-13 mm long,
10-11 mm wide; ovaries oblong, tapering basally, 2.5-3 mm long, pale cream;
stigma yellow. Fruiting spike elongate-globose, 2.5-5 cm long, 2-4 cm wide;
berries oblong-globose, 5-11 mm long, 5-7 mm wide. Germination epigeal
FLOWERING PERIOD. October - November.
HABITAT. In garigue and Pinus halepensis maquis; sea-level to 500 m
DISTRIBUTION. Balearic Islands (Majorca), Corsica, Sardinia, NW Italy
and an excerpt from something have in press:
Arum pictum L.f. is a distinctive autumn flowering species occurring in the
Balearic islands, Corsica, Sardinia and mainland western Italy. Although
unquestionably all belonging to one species the populations in the Balearics
tend to have rounded leaves with rather weakly defined rounded basal lobes
whereas populations from Corsica, Sardinia and mainland Italy have leaves
almost triangular in outline with quite well formed basal lobes. Given this,
the publication of a purportedly Majorcan endemic, Arum pictum subsp.
sagittifolium J.A.Rosselló & L.Sáez (Acta Bot. Barcin., 44: 170 (1997)) is
intruguing in that the specimen that forms the type has leaves with much
more the appearance of A. pictum from the easterly part of its range.
----- Original Message -----
Sent: Wednesday, November 17, 2004 10:30 AM
Subject: [Aroid-l] Arum pictum
> Hi folks -
> Was researching a bit and came across this Arum species. I have not been
> able to find out much information (guess I need to go check the library
> a copy of The Genus Arum, by Peter Boyce) about this autumn flowering bulb
> (the only one in the genus, apparently).
> Arum pictum appears to be native to Italy, Sardenia, and other western
> Mediterranean areas(?). The flowers are dark burgundy/black and the
> which follow are dark green with lighter veins and a distinct dark red
> to the leaf. Here are a couple of photos I've found:
> http://web.tiscali.it/leconchiglie/piante1/arum_pictum.jpg (leaves)
> Does anyone out there have experience with it?
> Thanks in advance,
> Seán O.
> h o r t u l u s a p t u s - 'a garden suited to its purpose'
> Seán A. O'Hara email@example.com www.hortulusaptus.com
> 1034A Virginia Street, Berkeley, California 94710-1853, U.S.A.
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