Hardy Aroids in the Garden Judy Glattstein

Though not showy plants and with only a modest following among plant lovers, the hardy aroids are interesting, display many virtues in cultivation, and attract "a different class of gardeners"

The Arum Family, or Araceae, consists of tion, especially in the United States. They about fifteen genera, most of them tropi- are, therefore, unusual and have the cal but of wide distribution. Some of the appeal of novelty. tropical members of the family have long Aroids contain a bitter substance, calci- been under cultivation, especially in east- um oxalate, and are little bothered by ern Asia and the Pacific Islands. Taro pests. Slugs, mice, rabbits, and deer find (Colocasia esculenta) and several species them decidedly unpalatable. When aroids of Xanthosoma (yautia), for example, are are used for food, the calcium oxalate grown for their edible tubers as staple first must be destroyed by heat. Garden- sources of starch. Other tropical species ers should be careful to wash their hands are handsome foliage plants used in the after handling berries or a bruised tuber. temperate zones for summer bedding (Ca- Once, after cleaning Aris~ma seeds, I ladium) or as houseplants (Aglaonema, inadvertently touched my mouth. The Dieffenbachia, Monstera, Philodendron). resulting unpleasant tingling and numb- Others are used by florists as cut flowers ness took several hours to wear off. (Anthurium, Calla~.I. My garden in Wilton, Connecticut, is Some members of the family are hardy, shaded by mature white oaks (Quercus notably Aris~ma, Arisarum, Arum, Lysi- alba). Understory trees are dogwood chiton, and Symplocarpus. The Araceae (Cornus florida) and black birch (Betula might seem a poor prospect for garden- lenta). The Araceae I raise are quite worthy plants to those familiar only with hardy in Wilton, which is situated in Ar- the skunk cabbage (Symplocarpus fc~tid- nold Arboretum Hardiness Zone 6 (-5 us) of New England’s swamps. I have en- Fahrenheit to 5 Fahrenheit). In fact, the joyed cultivating representatives of sever- temperature once dipped to -8 Fahren- al genera, some for their flowers, some for heit, and there were no losses. The soil in their foliage. the garden is a good loam, which I keep Aroids have a modest following, appear- mulched with leaves for a constant supply ing in an occasional article, mentioned of humus; as in most of Connecticut, the briefly in gardening books. Visitors to my pH is rather low (acid). Other plants I use garden have admired them; they have sev- in the garden include such American wild- eral points of appeal. Many of the aroids flowers as Trillium, Sanguinaria canaden- I discuss in this article are rare in cultiva- se (bloodroot), Hexastylis spp. (evergreen 28

gingers from the southeastern states), Northeast are low in phosphorus, and pot- Phlox stolonifera, Phlox divaricata, and ash is especially useful for tuberous many kinds of ferns. Other shade-tolerant plants. It is not safe to use bonemeal in plants, such as hostas, epimediums, and my garden because it attracts skunks, primroses, also do well under these condi- which dig up the tubers looking for bones. tions. They do not eat the tubers, but it is a nui- Since I have to obtain most of the a- sance to replant them. Nitrogen is ap- roids from abroad, I prefer to receive plied in the spring, in the form of dried them in the autumn. They are completely blood, cottonseed meal, or leather tank- dormant at this time, and the tubers travel age. Fertilization after the first year is usu- well and arrive in excellent condition. If ally not required. The constant mulch of they are shipped in the spring, there is leaves seems to keep the plants growing the risk that they will break dormancy in good condition. while in transit. New growth can be dam- An alternative way of obtaining these aged either by the confines of the ship- plants is to raise them from seed. I soak ping container, or by rot. As soon as the dried berries in a little tepid water for an tubers are received they are planted hour or so, until the coat softens. Then, I directly in the garden. The area is spad- rub the seeds gently between paper tow- ed over, and extra compost is added if els and separate the seed. Each berry necessary. I fertilize with muriate of has one to four seeds. I sow the seeds in potash and superphosphate. Soils in the a sterile mix of half potting soil and half

The familiar skunk cabbage (Symplocarpus foetidus) Lysichiton americanum in flower in the wild, Washing- of New England’s swamps. This and all other ton, D. C. photographs accompanying this article were taken by the author. 29

Jiffy-mix® or Pro-mix@, with enough sharp gressed from an asexual to a male and sand for good drainage. (I sow them thin- finally to a female state, remaining in the ly enough that I won’t have to prick them last state. Many plants-Ilex and Myrica, out for a year.) I cover the the seeds well, for example-have single-sexed plants water them, and wait. Fresh seeds will ger- that are either male or female and that minate promptly under growth lights. remain so for the life of the individual Older seeds will germinate more slowly, plant, a condition called "dioecious." The and outdoor conditions slow the germina- transitional nature of the sexual state of tion process somewhat. Arisxma is referred to as "paradioe- My biggest problem has been to keep cious."" the plants through their dormant stages. While the garden site may be quite Aris~rna damp, pot-grown plants rot with the great- In North America there are two species est of ease. At the same time, small tu- of Arisa?ma, Arisxma triphyllum, which bers dry out quickly. It is difficult to find has four subspecies, and Arisxma dra- the correct balance. Second-year plants contium of the southeastern states. can go into a prepared site in the garden Aris~ma triphyllum (Linnxus) Torrey and should begin flowering in their third is found from the Gaspe Peninsula, or fourth year. I have used this method southern Quebec and Ontario, Wisconsin with several species of Arisxma and with and Minnesota south to eastern Texas Arum italicum. Aris~ma seeds do not and southern Florida, growing in moist, need a period of stratification but will ger- shady woodlands. There are four sub- minate during the autumn they ripen if specific populations, with widespread hy- they are sown indoors. Sown outdoors in brid swarms. the autumn they will, of course, germi- Arisxma triphyllum ssp. triphyllum is nate the following spring. The production the most widespread. Its height varies of seeds is generous, one spadix of Ari- with growing conditions. I have seen sxma sikokianum having from one to specimens that were dwarf in the wild four seeds in a berry, for a total of five reach two feet in height in the garden with hundred eighty-seven seeds. Plants of Ari- richer soil and ample water. Typically, it s~ma sikokianum often begin to flower in has one or two leaves, each bearing three their third year. Once established, the leaflets, which are glaucous beneath. The plants are most agreeable. I have dug spathe may vary in color from green to one up in full bloom, potted it for a rock- green-and-purple striped, to chocolate garden show, and replanted it in the gar- purple. The name ’Zebrinum’ is often ap- den without any difficulty or damage to plied to cultivars whose spathes are the plant. purple to bronze and have whitish longitu- The flowering of Arisxma follows an dinal stripes inside. An interesting variant unusual pattern. Immature corms, from has recently been discovered by Peggy either seeds or offsets, are asexual and French in Wilton, Connecticut. It has pro- have a single foliage leaf. As corms in- nouncedly white-veined leaves and crease in size after their first year, they comes true from seed. reach sexual maturity, producing two The second subspecies, which I have leaves and one scape. Smaller (lighter) seen in several gardens, is Arisxma tri- corms are male, heavier corms are invari- phyllum ssp. stewardsonii. This is a ably female, the sexual state having pro- northern variant in which the spathe is 30

green and strongly fluted with white site. The leaf is solitary, three-parted, and ridges on the outside. It tends to appear a glossy mid-green; it appears after later in the spring than the other sub- flowering, which occurs early in June. species and grows consistently in moist The spathe is very beautifully marked sites. Its leaves are never glaucous. with pink and white stripes. Mature tubers The third subspecies is Arisa?ma make numerous offsets, which form a triphyllum ssp. pusillum, which grows in good-sized clump in a few years. the same habitat as Arisa?ma triphyllum Aris~ma sikokianum Franchet and Sa- ssp. stewardsonii, although farther south vatier comes from Honshu, Shikoku, and and at lower elevations. Its leaves, too, Kyushu in Japan. Mature plants have two are never glaucous. There are no ridges three- to five-parted leaves that often have on the spathe, and the coloring is nearly attractive silver markings. Its Japanese always completely green or completely name, yuki-mochi-so, means "snow rice- purple, occasionally with thin, green cake plant," in reference to the pure- stripes. white, clublike spadix. The spathe is a The fourth subspecies, Arisa?ma tri- deep chocolate brown on the outside, phyllum var. quinatum, has a very re- green shading to white inside. It flowers stricted range in the deep South, growing in late April and early May. in moist, shaded locations. It is smaller This is an extraordinarily beautiful than the other subspecies, and its leaves plant. In the garden, I combine it with the are usually five-parted and glaucous Japanese Primula sieboldii, especially beneath, although there may be the deep-pink forms that contrast so nice- fewer leaflets, and the the leaflets may ly with the dark spathe of the Arisxma. not be glaucous. The spathe is green and One colony is growing with the Japanese bears no markings. painted fem, Athyrium goeringianum ’Pic- Arisxma dracontium, the green- turn’, whose silver fronds complement the dragon, has a solitary leaf with seven to markings on the Aris~mn leaf. Seeds are nineteen segments. The spathe is more freely produced and germinate readily. tightly furled than in the previous species Plants that produce seeds are more resis- and is green, without stripes. The long, tant to cold and go dormant later than slender spadix protrudes and hangs down non-seed-bearing plants. The seeds are from this. Plants can reach an overall ripe before the berries turn red, which is height of three feet (0.9 m). fortunate because the growing season in In western China, Japan, and the Hima- Wilton is too short for the berries to red- layas, there are at least one hundred spe- den. cies of Arisxma, forty-two in Japan Arisa?ma thunbergii var. urashima alone. Some of them are among the most (Hara) Ohashi and J. Murata is found in beautiful, exotic, interesting, and easily the wild on the islands of Hokkaido, Hon- cultivated plants that could be grown in shu, and Shikoku. The leaf is solitary, with the garden. eleven to fifteen pedately arranged leaf- Arisxma candidissimum W. W. Smith lets of a dark, glossy green. It appears is a Chinese species discovered and col- with the flowers. The Japanese name of lected by George Forrest in Yunnan in the plant, urashima-so, refers to the 1914. It is found in pine forests, indi- odd-even amusing-flowers and is cating a preference for acid soil. Under based on a folk tale. Taro Urashima was cultivation, it does not need a very moist a young fisherman, and it is for him that 31

the plant is named. The dark bronze-pur Creech of the United States Department ple spathe of Aris~ma thunbergii var. of Agriculture introduced it into the urashima arches strongly over the spa- United States. The pseudostem may be dix, narrowing abruptly to a tail-like tip. up to two feet (0.6 m) tall and pale green The spadix has a threadlike appendage or pale green with "snakelike" purple mot- as much as twenty inches (50 cm) long tling. Plants with mottling are more that trails on the ground like a fishing attractive in the garden than those without line. It flowers in mid-May in my garden. it. It flowers in late April to early May. Seeds germinate freely. The tubers may One of my correspondents, with true Ori- make offsets. A colony of this variety is at- ental courtesy, has written, "I sent tractive, not only for the unusual flower yesterday a parcel with the plants. I think but for the attractive leaf. they are of less value in Japan but good Arisa?ma japonicum Blume and Ari- plant for shady garden." s~ma serratum Thunberg probably are Aris~ma ringens (Thunberg) Schott is one and the same species. A common noted in English literature as coming into and very polymorphic species, minor vari- growth as early as February or March. ants in color and size have been The colder winters in Connecticut must accorded specific rank in the past. Dr. keep it dormant over a longer period, as I

Arisaema sikokianum in the author’s garden. This Arisaema thunbergii in the author’s garden. Found beautiful Japanese species is native to the islands of wild on the islands of Hokkaido, Honshu, and Shiko- Honshu, Shikoku, and Kyushu. ku, it flowers in mid-May in the author’s garden. 32

have not seen any growth as early as laced with crystals of oxalic acid, which that. Its leaves are large, glossy green, renders them unpalatable, and I had and thick. Mature plants have two leaves, never had a problem with such animals both of which have three leaflets. Each before. I was ready to admit my guilt. leaflet ends in a little, threadlike tail. The Then, in mid-July, two large buds ap- spathe of Aris~ma ringens differs from peared. They grew swiftly and continued those of other members of the genus, hav- to grow, until the single leaf of each plant ing an inflated, curving upper part resem- was bigger than my outspread hand. The bling a very large snail shell. The main spathe and spadix appeared as rapidly. part of the spathe is green in forma The spathe reminded me a little owl, with prxcox, dark purple in forma sieboldii. the tip falling forward for the beak and an The spathe’s margins are folded over like opening on each side resembling the an auricle and are chocolate brown. The eyes. It was a fine plant, but anonymous! leaves are unaffected by a light frost but Ohwi’s Flora is for Japan, and this was are damaged when temperatures drop a plant from mainland China. When in below 28 Fahrenheit. The tubers of Ari- doubt, find an authority, I told myself. I sa’ma ringens have grown larger than took some photographs and sent them off those of any other species of Arisa?ma I to H. Lincoln Foster, the doyen of Amer- have raised, reaching three and one half ican rock gardeners. He replied in early inches (8.5 cm) in diameter. Offsets are August: formed to a moderate extent. By studying my xerox of the pages of Aris~ma fargesii, which is native to Flora Republicae Popularis Sinicae con- the even the Mount Omei in China, is the least com- ceming arisaemas, though text is Chinese, from the rather good mon I grow. Carla Teune, curat- species drawings I feel confident that your plant or of the Leiden Botanic Garden, sent me is from the Section Franchetiana. This some seeds she had collected in China has 6 species, including candidissimum. in 1980, among which were seeds of an Your species is, I think A. fargesii. unidentified of Arisa?ma. species (Since A name! An identity! Though one plant the spathe is an important character for had male flowers and the other female, of a identifying species Arisa?ma, fruiting there has not been any setting of seed. cannot be identified with a plant The foliage is very tender, being killed by taxonomic key.) The seeds germinated the first light frost. well, but some plants succumbed to the winter. Each winter I lost a few more Arisarum tubers from rot. in Finally, the fall of The genus Arisarum A. Targioni-Tozzetti I felt that the two tubers 1983, remaining contains three species, all of which are were large enough to be put into a propa- confined to the Mediterranean basin. One gating-holding bed. May 1984 came and (Arisarum proboscideum) is, however, as did but there was no went, June, sign hardy in my garden. of either remaining tubers. The winter Arisarum proboscideum (Linnaeus/ Savi had been too cold for them, I thought, is often called the mousetail arum. Small- and I hadn’t them planted deep enough. er (more dwarf) than most species of Ari- I them from the Or should have protected sxma, it has a creeping rhizome and and that many mice, voles, chipmunks sends up a mass of small leaves. The I that the latter infest my garden. doubted spathe has a threadlike tip that protrudes are was true, for all parts of an Aris~ma from the leaves and looks rather like a 33

mouse’s tail. Culture is similar to that members of Arisa?ma, which is to say, woodland conditions of soil high in organic matter, moist but not soggy, and shaded.

Arum The genus Arum Linnxus consists of approximately twelve species, most of them native to the Mediterranean basin, two to the British Isles. All are tuberous. Their flowers are unisexual, but unlike that of Arisxma the spadix Arum bears both male and female flowers. Arum maculatum is the species com- monly found in Great Britain. The large, green, arrow-shaped leaves emerge in the spring. Often the leaves are splashed with black or purple spots. Flowering oc- Arisaema japonicum in the author’s garden, Dr. John curs soon afterward. In autumn, clusters Creech of the United States Department of Agricul- of brilliant orange-red berries appear and ture introduced this to the United States. species make a handsome display. Arum macu- latum is valuable as a garden plant because it will grow and fruit in heavy shade. Arum italicum (as Arum italicum ssp. neglectum) is less commonly found in the British Isles. Arum italicum ssp. itali- cum, the form occurring in Europe, has green leaves with veins marked in creamy white; it is thus the more inter- esting garden plant. In addition, its leaves begin their growth in the autumn, persist through the winter, and go dor- mant in midsummer. If an exceptionally bad season destroys the foliage over the winter, a secondary set will emerge in the spring. The spathe varies in color from creamy white to pale green. The berries of this species also give a handsome display in autumn. Two especially attrac- tive leaf forms have been given cultivar Close-up of the flower of Arisaema fargesii in the names, ’Pictum’ and ’Marmoratum’. Be- author’s An uncommon it hails garden. species, from cause of the autumn berries and winter Mount Omei in China. This plant was grown from seed collected in China by Carla Teune of the Leiden foliage, this is a choice species for Botanic Garden. adding interest to the shady woodland 34

garden. The seeds ripen in autumn and gardener. Perhaps other gardeners will be- germinate the following spring. come interested enough in these plants through this article to attempt to cultivate Pinellia them, as well as other hardy species, and The genus Pinellia consists of perhaps would be willing to share their information half a dozen species native to China and with me. Japan. The leaves appear with the flow- ers, which are monoecious. The leaves Sources Alfred Evans. The Peat Garden and Its Plants. are simple or three- to seven-lobed. London: Dent, 1974. xi + 164 pages. Pinellia ternata and Pinellia tripartita Andrew Henderson. Dragon plants and mousetails. are the two species listed in Ohwi’s Flora The Garden, Volume 106, Number 1, pages of Japan. Both are small plants four to 13 to 17 (January 1981).(. eight inches (10 to 20 cm) tall. Their roots Donald C. Huddleston. The North American of Arisxma are additional small tubers are species /Araceae)-"Jack-in-the- tuberous; Pulpit." Aroideana, Volume 7, Number 1, at level. In both produced ground pages 15 to 17 (1984). species, the leaves are green and three- Will Ingwersen. Lords and ladies in the garden. lobed. Owhi mentions Pinellia ternata as Country Life, pages 1,654 to 1,655 (June 7, quite common in cultivated fields and 1984). roadsides. This, with its habit of Tokujiro Maekawa. On the phenomena of sex coupled transition in Aris~ma japonica Bl. joumal of extra tubers at the soil surface producing the College of Agriculture, Hokkaido Imperial might indicate a certain weediness. University, Volume 13, Number 3, (June Spathes are green or purplish. Flowering 1924). occurs in summer. Brian Mathew. Dwarf Bulbs. London: Batsford, for the Horticultural 1973. 240 In November 1986 a friend sent me Royal Society, pages. some tubers of Pinellia cordata from Ja- . The Larger Bulbs. London: Batsford, in pan. While I have not yet found any refer- association with the Royal Horticultural ences to this species (Hortus Third, for Society, 1978. 156 pages. example, does not list Pinellia at all), I S. J. Mayo. A survey of cultivated species of Aris~ma. Plantsman, Volume 3, Number 4, assume that Pinellia cordata has simple pages 193 to 209 (March 1982). rather than lobed leaves. to According Nicholas Nickou. A unique jack-in-the-pulpit. my friend, people generally raise it in Bulletin of the American Rock Garden pots in Japan, apparently to have easy Society, Volume 43, Number 3, page 138 access to the fragrant plants. (Summer 1985). Ohwi. Flora Edited Frederick Nowhere have I found reference to the Jisaburo of Japan. by G. and H. Walker. I Meyer Egbert Washington, pleasant aroma that this aroid has. D. C.: Smithsonian Institution, 1965 (reprinted smelled it for the first time in Lincoln and 1984). ix + 1,067 pages. Laura Louise Foster’s garden during the summer of 1986, at the suggestion of my friend Takeo Nihei, who was visiting the United States at the time. Obviously, Judy Glattstein is a landscape consultant who spe- the use there is more to a plant than its botanical cializes in perennial-border design and of native plants in the landscape. An avid horticulturist, description. she chairs the Connecticut Chapter of the Ameri- The aroids are not hardy splashy, can Rock Garden Society and teaches at the New showy flowering plants like roses or chrys- York Botanical Garden and the Brooklyn Botanic anthemums. They have a different kind of Garden. flower, interesting to a different class of