In the wild, most aroids (arum family members) live in tropical forests. To see them you'd have to search dimly-lit forest floors or look up to see vines climbing trees or epiphytes in the canopy. These three niches are home to the majority of the 3,700 plus species making up the splendidly exotic, notably diverse Araceae family.
Some aroids are hardy enough to survive in temperate climes; Arum italicum, Arisaema and British A native plant is one that originated or arrived naturally in a particular place without human involvement. In the British Isles, native plants are those that were here during the last ice age or have arrived unaided since.
Many tropical aroids make handsome and amenable long-term houseplants; they can be divided into those grown mainly for their blooms, and those grown for foliage.
Flowering aroids
If you have a peace lily (Spathiphyllum), calla lily (Zantedeschia) or flamingo flower (Anthurium), you already grow a tropical aroid. All show characteristic spadix and spathe inflorescences and are stylish additions to the home. Peace lily blooms are white, but breeding work in the other genera is producing spathes in an ever-widening colour range.
Flamingo flowers (Anthurium) – have spathes in white, red, pink, green, chocolate-brown and purple, all easy to grow in bright but indirect light. Spathe shape varies from round to teardrop-shaped, with a crinkled texture in some cultivars. Foliage is usually glossy and arrowhead-shaped. Most are complex hybrids from Central American Anthurium andraeanum, hence Andraeanum Group. Typically plants reach 60cm in height and width, but there are more compact ones half this size, such as purple-flowered Zizou (‘Anthevex’). Anthurium crystallinum is an epiphytic species grown more for its lovely leaves – heart shaped and dark green with paler veining – than its greenish flowers. It can climb to 50cm. Anthuriums do best at 16–22°C.
Peace lilies (Spathiphyllum) are among the easiest of all house plants. They send up long-lasting, pure white spathes cupping spiky little cream spadices, above glossy, elongated leaves. Most widely grown is S. wallisii; its Gardeners often use the word variety when referring to a specific plant, but the correct botanical term is 'cultivar'. Whichever word you use, it means a distinctive plant or plants, given a specific cultivar name and usually bred to enhance certain characteristics, such as flower or fruit size, colour, flavour or fragrance, plant size, hardiness, disease resistance, etc. Additionally, it is worth knowing that, botanically, variety has another meaning - it refers to a naturally-occurring distinct plant that only has slight differences in its looks. For example, Malva alcea var. fastigiata differs from typical plants by having an upright habit.
Calla lilies (Zantedeschia) hybrids: relatives of white-flowered arum lily (Z. aethiopica), compact and colourful calla lilies have Z. elliottiana and Z. rehmannii in their ancestry. Breeding work has produced an explosion of new hybrids in yellow, pink, red, purple, orange and near black, plus pastel bicolours, some delicately vertically striped. Some show marked colour changes as spathes age, and flecked foliage. Callas can also do well outdoors used as Bedding plants are usually colourful half-hardy, short-lived or annual plants, grown for displays in beds or containers. They may be changed seasonally, with spring, summer and winter bedding displays each using different plants of appropriate hardiness and flowering times.
Frost-free environments, such as a cool greenhouse or conservatory, have a nighttime minimum of 4°C (39°F). This is ideal for plants tolerant of low temperatures, but will not survive being frozen, such as tender plants being overwintered including pelargoniums; frost-tender rooted cuttings such as penstemon; and bedding plants in spring.
The definitive feature of the Araceae family is their compound flowers, or inflorescences; each bloom is made up of many tiny flowers.
Aroid inflorescences are formed of a fleshy central column (a spadix) of many tightly packed flowers.
A spadix is usually surrounded by a brightly-coloured spathe (a highly modified leaf). Not all aroid species have spathes, but all have spadices.
Foliage aroids
Many aroids are grown primarily for their foliage and will grow well in dimly-lit corners few other house plants can tolerate. They can cope with irregular watering and put up with dry indoor air, making them among the most useful and lowest-maintenance of all indoor plants.
Alocasias, some of which are large-leaved plants known as elephant’s ears, prefer warm, humid conditions, regular misting and good but indirect light. Alocasia × amazonica ‘Polly’ has striking pale veining on dark green, spearhead-shaped leaves to 30cm long; minimum 16°C. Alocasia lauterbachiana is a handsome plant with narrow, upright, wavy-edged leaves, undersides and stems a contrasting red. Grows to 1.5m; ideal temperatures are 20–25°C; keep above 15°C.
Dieffenbachia: dumb A cane is a slender, straight, length of woody plant material, usually bamboo. Canes are primarily used as plant supports. The fruiting stems of blackberries, raspberries and hybrid berries (such as loganberries and tayberries) are also known as canes, so these crops are often referred to as cane fruit.
Epipremnum (devil’s ivy) is a climbing vine that will trail attractively, or grow up a moss pole. Also known as Ceylon creeper, it is extremely tough and shade tolerant. It is an excellent plant for beginners or for brightening dark corners. Epipremnum aureum has irregular yellow Variegated means having leaves or other plant parts with streaks, blotches or patches of different colours. Typically, these would be a combination of two colours, such as green and gold or green and white.
Monstera contains the undisputed heavyweight champion of the indoor garden: M. deliciosa (Swiss cheese plant). Large, well-grown specimens can single-handedly transport a room to the tropics. The biggest, most perforated leaves will be on mature plants grown in good light and high humidity. A far more compact relation, usually sold as ‘Monkey Mask’ also has holes in the leaves, but these do not reach the leaf margins as in M. deliciosa. The look is lacy, unusual and attractive. ‘Monkey Mask’ likes high The concentration of water vapour in the atmosphere. This affects the rate at which plants transpire (lose water from their leaf pores), which in turn affects how much water their roots absorb from the soil. If air humidity is low, plants transpire quickly and become at risk of wilting if water is lost from the leaves faster than it can be absorbed by the roots. Different plants require different levels of humidity to thrive. Many tropical houseplants need high humidity and are best grown in a steamy bathroom, misted regularly or placed on a saucer of damp pebbles. In a greenhouse, humidity can be raised in hot weather by damping down (wetting) the floor or overhead misting.
Philodendron is a large genus of plants in a wide range of sizes and bold leaf shapes. Some thrive in even the darkest corners. Philodendron bipinnatifidum (tree philodendron; syn. P. selloum) rivals Swiss cheese plants for scale indoors – its huge leaves grow to 1m across. Tree philodendron copes with shade; in a pot it makes around 1.5m. An attractive Variegated means having leaves or other plant parts with streaks, blotches or patches of different colours. Typically, these would be a combination of two colours, such as green and gold or green and white.
The ZZ plant or Zamioculcas zamiifolia is a species that marries architectural, glossy green looks with drought tolerance. The upright, pinnate leaves grow to 45–60cm and it even tolerates deep shade. It is best at 18–26°C; minimum 15°C. Zamioculcas zamiifolia Raven (‘Dowon’) is aptly named for its dark purple to near-black, gothic foliage. Every plant was micropropagated from a single leaf mutation on a plant on a South Korean nursery in 2006, but not introduced until 2017. New leaves emerge green, turning dark over six to eight weeks, even when grown in shade.
This article first appeared in the January 2020 issue of The Garden magazine – an exclusive monthly publication for members of the RHS.
