Arum is a genus with tuberous roots in the Araceae family. There are about 25 species found from Europe to central Asia.
Arum apulum is an endemic species of central Apulia, related to Arum nigrum from the Balkans. It occurs in sparse woodland areas, being a shade loving plant. It follows the classic pattern of many Mediterranean geophytes, with summer dormancy. Leaves appear in October and flowering is in April. Listed as critically endangered (CR according with the IUCN Red List Categories) in the Italian Red Book of Plants. Photos taken in habitat by Angelo Porcelli.
Arum concinnatum is native to the Eastern Himalaya to Burma (southern Greece to southwest Turkey. It flowers in Canberra, Australia in Mid October. Unfortunately I find that the spathe approaches transparency rather quickly. Grown and Photographed by Paul Tyerman.
Arum creticum is native to Greece and southwest Turkey where it blooms in April to May. It has unmarked, dark green leaves and produces fragrant, bright yellow to yellow-green to green-white spathes. Photos 1-2 taken March 2008 by Jay Yourch. Photos 3-4 from Paige Woodward of plants descended from material collected on the Greek island of Karpathos in 1953. She writes that this fragrant plant that grows to a height of 25-35 cm (10-14") prefers sun and deep, somewhat alkaline soil. She grows her plants in a cool greenhouse kept dry and dormant in summer, watering again in November and has found them hardy to Zone 6. The last photo was taken by John Lonsdale.
Arum cyrenaicum SW. Kriti, NE. Libya flowers in Canberra, Australia in late September. A rather delicate shading of purple on green. Grown and photographed by Paul Tyerman.
Arum dioscoridis from the Eastern Mediterranean found in rocky scrub flowers in Canberra, Australia in early November. The creamy yellow spathe with heavy purple markings is striking and attractive. Unfortunately the smell is rather the opposite and is somewhat unpleasant. The first photo was taken by by Paul Tyerman and the second by Susan Hayek for Diana Chapman.
Arum hygrophilum NE. Morocco, E. Cyprus, SW. Syria to W. Jordan photos one and two below from Kelly Irvin and three and four from Paul Tyerman who writes: “ Arum hygrophilum flowers in Canberra, Australia in June or July. My form is rather different to Kelly Irvin's as it is green with purple edging rather than that rather interesting creamy white of Kelly's.
Arum italicum is a widespread plant of woods and hedges in Europe, North Africa and Asia Minor. It is a very variable species. It can have dark plain green leaves or with whitish-cream stripes. Some plants are particularly variegated and often referred as 'marmoratum' or 'pictum', but both names are invalid. Variegated specimens grow usually smaller, but the plain green ones can get to an unusually large size in moist and shaded spots, rivaling Zantedeschia. It is also grown for its fruit as plants in fruit are very attractive. The first photo was taken in habitat, Apulia, Italy by Angelo Porcelli. The second and third photos were taken by Angelo Porcelli and Jay Yourch showing the beautiful variegated leaves.
Arum italicum ssp. albispathum From Telos Rare Bulbs and grown by Arnold Trachtenberg. This subspecies has leaves that are plain deep green, never marked in any way and a spathe that is almost white and a spadix-appendix that is pale yellow
Arum italicum ssp. italicum is the most widely grown subspecies. In an article in The Plantsman, Peter Boyce, an expert on this genus suggests that he now believes another of the subspecies, ssp. neglectum should by included in ssp. italicum as wild plants show considerable variation making the usual distinction between the two difficult.
The plant pictured below is form sometimes referred to in Italy as 'marmoratum'. This form is cultivated for its beautiful leaves that are have white to yellowish (ivory) main and secondary veins. The leaves appear in autumn and last through the winter months into spring and summer. Easy to find and to grow here in Northern Italy. The light yellow coloured spathe, appearing in May in northern Italy, lasts only one week. The second picture is a closeup of the flowers; in a few days the spathes are drying. Photos by Giorgio Pozzi, May 2006.
Two attractive cultivars of this subspecies are shown below. In 'Gold Rush' the veins and the surrounding areas on new foliage are heavily marbled in gold, fading to cream. 'McClements' has dark green leaves with bright white veins and black spots over the surface. Photos by Graham Rice.
Pollination is achieved by producing the scent "rotting material", attracting flies and then imprisoning them behind hairs for 24 hours. Incoming flies are hopefully carrying pollen from other plants. Before they are released they are exposed to pollen from the plant holding them. At various stages of this process heat is produced, for example to evaporate the odour producing chemicals. The fact that the plants are thermogenic was known to Lamarck in 1778. The temperature difference between the yellow appendix and the surroundings is above 15 °C. Photographs by David Pilling. The first two show the floral chamber before and (6 days later) after pollination. The next one (of a different plant), taken around 9:40PM when the ambient temperature was about 11 °C, records the reading on an infra-red thermometer. Photo four is of a bulb with offsets, the bulb is over an inch in size; the final two photos show seed pods and seed on a 10 mm grid; typically there are four seeds per pod. Cleaning the seed is a job best done wearing protective gloves; all parts of the plant contain the irritant calcium oxalate, this is not a problem for normal gardening activities. Crystals of calcium oxalate are known in plants as 'raphides' and are found in many species.
A fresh flower was opened up, inside were lots of small flies which had fled by the time the photo was taken.
Arum korolkowii is a species of N. Iran, Afghanistan and C. Asia (to northwest China). Photos by Arnold Trachtenberg.
Arum lucanum is a very elusive species of Southern Italy, growing on rather high elevation habitats (pastures), usually well over 1000 m (3300 ft). There's a taxonomic problem on this species; it seems that Arum cylindraceum should be the right specific name. Peter Boyce discusses this question in his monograph, The Genus Arum. Photos taken in habitat in the Pollino Mountains by Angelo Porcelli.
Arum maculatum photos were all taken 1.02.04 in the beech woods surrounding Cologne, Germany, where they are widely distributed and show considerable variation in leaf spotting and form. Typically, the leaves die-back completely in Summer. Photos: Jamie Vande, Cologne show typical clumps emerging from leaf litter, a finely spotted clone with rounded leaves, a better splashed form with arrow-shaped leaves, even a colony without spots. The soil is a loose, sandy loam covered by a 10cm(4") leaf litter. One can literally dig with their hands! Although I've not tested it, a beech forest is typically acid.
Arum nigrum Native to the Balkans. These magnificent plants (pictured here) descend from material collected in cracks of Karst formation in the Dalmatian coastal range, north of Knin, Croatia. That was in 1982, since then the area has been devastated by war. Blooming in May - June, the spathe, gleams purple-black and encloses a pale spadix. Photos and text from Paige Woodward.
Arum orientale EC. Europe to W. Caucasus flowers in Canberra, Australia in mid September. Grown and Photographed by Paul Tyerman.
Arum palaestinum is a species from Israel W. Syria, Lebanon to Jordan. The first two photos shows one grown under HID lights and photographed by Arnold Trachtenberg. The third photo was taken by Susan Hayek for Diana Chapman.
Infrared image of Arum palaestinum showing heat generated by spathe as part of the pollination strategy. Photographed by Arnold Trachtenberg.
Arum pictum is the only autumn flowering member of this genus. It also has a characteristic purple edge to the young leaves. It grows in Corsica, Sardinia and the Balearics in rocky places. Grown and photographed by Rob Hamilton.
Arum purpureospathum is endemic to the island of Crete. Photos 1-3 were were contributed by the UC Botanical Garden. Photo 4 was taken by Nhu Nguyen at the UC Botanical Garden of the plants blooming in early April.
This species is quite interesting over a long period of time. In my northern California garden the large leaves appear in September. They are very shiny and even look nice when rained on. Flowering occurs between November and February depending on the year. In the third photo below the leaves are dying but the plants have green fruit in April. By July the fruit has turned red but in between at times the fruit was green and red. The last photo shows the seeds on a 1 cm. grid. Photos by Mary Sue Ittner.