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.