Hosta (syn.: Funkia) is a genus of about 23–40 species of lily-like plants native to northeast Asia. They were once classified in the family Liliaceae but are now included in the family Agavaceae by the Angiosperm Phylogeny Group. The scientific name is also used as the common name; in the past they were also sometimes called the Corfu Lily, the Day Lily, or the Plantain lily, but these terms are now obsolete. The name Hosta is in honor of the Austrian botanist Nicholas Thomas Host.The Japanese name Giboshi is also used in English to a small extent. The rejected generic name Funkia, also used as a common name, can be found in some older literature.
Hostas are herbaceous perennial plants, growing from rhizomes or stolons, with broad lanceolate or ovate leaves varying widely in size by species from 1–15 in (3–40 cm) long and 0.75–12 in (2–30 cm) broad. Variation among the numerous cultivars is even greater, with clumps ranging from less than 4 in (10 cm) across to more than 6.5 ft (2 m) across. Leaf color in wild species is typically green, although some species (e.g., H. sieboldiana) are known for a glaucous waxy leaf coating that gives a blue appearance to the leaf. Some species have a glaucous white coating covering the underside of the leaves. Natural mutations of native species are known with yellow-green ("gold") colored leaves or with leaf variegation (either white/cream or yellowish edges or centers). Variegated plants very often give rise to "sports" that are the result of the reshuffling of cell layers during bud formation, producing foliage with mixed pigment sections. In seedlings variegation is generality maternally derived by chloroplast transfer and is not a genetically inheritable trait.
The flowers are produced on erect scapes up to 31 in (80 cm) tall that end in terminal racemes. The individual flowers are usually pendulous, 0.75–2 in (2–5 cm) long, with six tepals, white, lavender, or violet in color and usually scentless. The only strongly fragrant species is Hosta plantaginea, which is also unusual in that the flowers open in the evening and close by morning. This species blooms in late summer and is sometimes known as "August Lily".
Hostas are widely-cultivated ground cover plants, particularly useful in the garden as shade-tolerant plants. Hybridization within and among species and cultivars has produced numerous cultivars, with over 3000 registered and named varieties, and perhaps as many more that are not yet registered. Cultivars with golden- or white-variegated leaves are especially prized. Popular cultivars include 'Francee' (green leaves with white edges), 'Gold Standard' (yellow leaves with green edges was discovered by Pauline Banyai) 'Undulata' (green leaves with white centers), 'June' (blue-green leaves with creamy centers), and 'Sum and Substance' (a huge plant with chartreuse-yellow leaves). Newer, fragrant cultivars such as 'Guacamole' are also popular. Pictures of hosta species and cultivars, along with other information, may be found at http://www.hostalibrary.org.
Hostas are notoriously a favourite food for deer, slugs and snails, which commonly cause extensive damage to hosta collections in gardens. Poisoned baits using either metaldehyde or the safer iron phosphate work well for the latter, but require repeated applications. Deer control tends to be variable, as anything other than fencing tends to work for a few years then cease to work as they become accustomed to it.
Foliar nematodes, which leave streaks of dead tissue between veins, have become an increasing problem since changes in attitudes about pesticides since the mid-1990s in many countries have caused a resurgence in this once-controlled pest. There are no effective means for eliminating nematodes in the garden, although they can be controlled to the point where little or no symptoms are seen. A virus called Hosta Virus X has become common since 2004 and plants that are infected must be destroyed. It can take years for symptoms to show, so symptomless plants in infected batches should also be considered infected.
Otherwise they are generally easy and long-lived garden plants, relatively disease free, requiring little care other than watering and some fertilizer to enhance growth. Some varieties are more difficult to grow, as can be expected with 5,000+ cultivars, but most are easy enough for beginners.