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Aspidistra

An annotated list of the species and cultivars

Introduction

The monocot genus Aspidistra is part of the lily family, Liliaceae although that family is so large that it is usually broken down into smaller families, placing Aspidistra in the Ruscaceae (which has priority over Convallariaceae).

Aspidistra species inhabit the floors of east Asian forests from eastern India, Indo-China, China and Japan. Aspidistra is one of those genera that has been ignored by field botanists until quite recently, and there has been a very rapid rise in the number of recognised species in recent years. Most books state that there are 8 to 10 species, which represents our knowledge up to the late 1970s. Then in the 1980s 30 new species were described from China. Based on current knowledge, China has the most species with some 59, of which 54 are endemic. The biodiversity 'hotspot' of the genus seems to be Guangxi Province, from where no less than 39 species have been described. New species are still being found, and the focus has shifted to Vietnam, from where 25 new species have recently been described with two more awaiting formal description. Presently only one species A. dolichanthera, has been recorded from China and from Vietnam but there are likely to be more  species common to neighbouring Guangxi and Cao Bang provinces. 

Currently 91 Aspidistra species have been formally described, and it has been speculated that there may be more than 100.

With the current uncertainty as to the number of extant species and variation inherent within species, Aspidistra must be seen as a genus in flux. The genus has not been studied sufficiently well to allow species properly to be delimited. Published keys do not always work well and descriptions, at least those available in English, are often inadequate. Even with recent floras it is impossible sometimes confidently to assign cultivated plants to a particular species even when the flowers have been seen. At the same time a wealth of new material is becoming available from nurseries and new Aspidistra sp. are entering commerce before they have been formally named. A consequence of all this is that there is uncertainty about the identity of some of the material available commercially.

Flowers

Aspidistra flowers are well worth watching out for because of their intrinsic interest and because it is only by examining the flowers that there is any chance of assigning an Aspidistra to a species.

Aspidistra flowers are usually borne at soil level and may need to be partially excavated to see them properly. Particularly with a new plant of unknown flowering season it is necessary to watch for the flowers developing as, depending on species and treatment, they may appear almost at any time of the year. In many species the flowers are sombrely coloured so they are easily overlooked but in others they are vivid and with 6 to 14 lobes they can resemble little stranded starfish or sea anemones.  In a small number of species the flowers are held well above the ground.

Aspidistra flowers show remarkable interspecies variation. The basic structure of an Aspidistra flower is a little unusual.  The flowers are borne singly on a peduncle that arises directly from the rhizome of the plant. The peduncle has occasional bracts along its length, two or three of which usually subtend the terminal flower. The flower itself is composed of an essentially cup- or bell-shaped structure called a perigone. In the perigone, sepals and petals are not differentiated but it is useful to think of the perigone as being composed of tepals. The tepals are fused together basally to form a tube but are free apically and their tips are more or less extended into perigone lobes. For a given species there is a standard number of tepals and, by extension, perigone lobes but the number can vary 1 or 2.  The standard number of tepals is based on multiples of 3 or 4 depending on species.  The lobes appear to be biseriate in some species.

Within the perigone are a single central pistil and a number of stamens. The stamens are borne on very short filaments that arise usually towards the base of the perigone tube at a position corresponding with the mid-line of each constituent tepal. Except in one case, the number of stamens therefore corresponds with the number of tepals even in flowers with a non-standard number of tepals.  The exception is A. dodecandra where the number of stamens is reportedly twice the number of tepals (but see also A. typica).

Aspidistra pistils (stigma, style and ovary) are remarkably varied.  The ovary is usually inconspicuous but the style and stigma are of great significance taxonomically.  It is not obvious whether it is the style or the stigma that is elaborated (discussion here).

Depending on species Aspidistra styles have 3 or 4 terminal lobes although they may be deeply emarginate or otherwise decorated so that the margin may seem to indicate many more lobes.  The true number of stylar lobes is usually much clearer viewed from below.  As with perigone lobes each species has a standard number of stylar lobes but the number can vary 1.  Aspidistra styles vary from simple, slender columns to intricately sculpted, massive structures occupying most of the perigone tube.

There is great variation in the shape and size of the perigone and particularly in the structure of the style. For example, the perigone may be open like a shallow bowl (A. saxicola) or closed over with a tiny opening (A. minutiflora), it may be tubular (A. tubiflora) or spherical (A. longanensis ). The perigone lobes may be non-existent (A. connata) or several cm long (A. longiloba). The style may be 3- or 4-lobed (A. triloba cf. A. sichuanensis), tiny (A. retusa) or so large that it closes off the perigone tube (A. elatior), it may be flat (A. cruciformis), bowl-shaped (A. attenuata) or domed (A. lurida), its surface may be smooth (A. nicolai ) or intricately sculptured (A. patentiloba). These differences, crucial to identification of species, may be visible only under a hand lens and after the flower has been partly dissected.

Aspidistra flowers are usually hermaphrodite with the stamens hidden below the relatively large style but in a few cases the stamens are prominent.  In at least one species, A. fungilliformis, it is reported that flowers are sometimes unisexual.

Very little is known about Aspidistra pollination biology.  The rarity of fruits in cultivation may be due to lack of pollinators or pollinizers, or both.  It would be interesting to know the origin of the great myth associated with Aspidistra flowers, that slugs and snails pollinate them. They do not.  Research in Japan has shown that tiny terrestrial crustaceans called amphipods are responsible for pollinating Aspidistra elatior. Australian amphipods have also been shown to pollinate introduced Aspidistra sp. and collembolans may also be implicated. Fungus gnats have also been suggested as possible pollinators.  An obvious scent has been reported only for a few species (A. campanulata, A. patentiloba, A. stricta).

Cultivation

Aspidistra are mainly adapted to a life of forest gloom and seasonal drought and they are indeed tough and resilient plants. However, it is most unfortunate that Aspidistra have the reputation for thriving on neglect in some dark corner; they may survive such conditions but they certainly don't thrive. They also have a reputation for being boring plants. Given good growing conditions they are lovely and extremely interesting plants!

Aspidistra are thought of almost exclusively as house plants (at least in the UK) but many are surprisingly cold tolerant.  Aspidistra elatior easily withstands a few degrees of frost and species from mainland China are likely to be considerably more cold tolerant.  The larger species are therefore worth trying in the garden in a shady (but not too shady!), sheltered and well-drained spot. Smaller species are better grown in pots which facilitates close inspection of their fascinating flowers.

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last updated 02/10/2008