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A Summary of the genus Shortia (Diapensiaceae)

Contents

Introduction
The genus
Cultivation & Propagation
Key to the genus
The species
References


Few would deny the considerable beauty of this small genus, but it has never become widely established in horticulture. Its reputation for tricky cultivation, not altogether justified, means that shortias are found mainly in the gardens of connoisseurs, on show benches and in botanic gardens. Like many genera where there is a fairly strong overall similarity, the taxonomy of the individual species and subordinate taxa is both confused and confusing and is such that most popular books of reference are of little help. There are many names, especially for the lesser entities within Shortia soldanelloides, and it is unclear whether all these names represent distinct taxa or merely pauses on a long glissando of variation. In this article I make no claim to resolve this question, but follow what appears to be a general consensus to bring together reliable information on the taxa that are currently recognised as distinct. Consistent descriptions are provided together with a key to the species and most of the subordinate taxa.

The genus

Shortia, of the family Diapensiaceae, was founded in 1842 by the American botanists John Torrey and Asa Gray, based on a specimen found in the Paris herbarium during a visit by Gray. This was a fruiting specimen collected in North Carolina in 1788 by Michaux, and it was named Shortia galacifolia from the resemblance of the foliage to that of the allied genus Galax. The generic name commemorates Charles Wilkins Short (1794-1863), a doctor and amateur botanist who had corresponded with Gray for many years.

Shortia Torrey & Gray

A genus of six species, one in the eastern USA, the others in eastern Asia. Mat- forming perennials with evergreen, alternate, rounded or elliptic, more or less toothed leaves. Flowers solitary or in a short raceme on a scape with several persistent bud scales at the base and a few small bracts near the top. Calyx lobes 5, corolla funnel-shaped with 5 more or less spreading, toothed or fringed lobes. Stamens 5, attached near the mouth of the corolla tube, usually alternating with 5 short staminodes at the base. Capsule globose, 3-valved, dehiscent, style persistent in fruit. Seeds numerous, small, oblong or ovoid. The teeth are generally sharper and more prominent on immature leaves and it is the mature foliage that is described below. The number of teeth is that on one margin of the leaf.

For many years, some of the Asian species were separated in the genus Schizocodon Siebold & Zuccarini, but few authors maintain this genus now. The main distinction is that the seeds are somewhat winged in Schizocodon but not in Shortia in the restricted sense; also, although several other species have in the past been placed in Schizocodon, this genus is now restricted by those who maintain it to S. soldanelloides, the only species that normally bears more than one flower on each stem. Several of the minor taxa within S. soldanelloides were described under Schizocodon and appear not to have been formally transferred to Shortia.

Cultivation

As is often the case, much may be inferred from the natural habitats of the species to guide the intending cultivator of these plants. In nature the North American S. galacifolia occurs in similar habitats to many of the Asian species, namely broad-leaved deciduous or mixed forests in low mountains. Common associates of the American species include Mitchella, Galax and species of Asarum. Interestingly, in Japan too, Shortia may be seen growing with Asarum and Mitchella. Most species are characteristic of moist yet well-drained habitats in areas of high rainfall. References to the home of S. galacifolia describe it as forming mats of foliage on steep ravine sides and on stream banks - very much the kind of conditions in which S. soldanelloides can be seen in Japan. However, there is a greater diversity of habitat in the latter species and this is reflected in a wide range of variation.

For the gardener, the natural combination of moisture, good drainage and sun is often a little awkward to achieve. In areas of naturally high rainfall it is less of a problem and a soil with a high content of coarse acid leafmould and some sharp sand will suit the plants well. In such a situation a position in full sun may be acceptable - the plants will then flower more freely and the foliage colour better than in the shade. In drier areas a similarly retentive soil is needed but light shade is advisable as well as careful attention to watering in dry weather. In either case, young plants should be grown on in a shady nursery bed until ready for their final planting.

Propagation

The difficulty and especially the slowness of shortias to propagate is surely the chief reason that they are not more commonly seen in gardens and nurseries. Both seeds and vegetative means may be employed but neither is ideal. The seeds are tiny and it has been observed that they are often retained in the capsule, sometimes even germinating there. Shortias also have a mycorrhizal association - a symbiotic relationship with a soil fungus - but it is not clear whether this is a significant factor in seed germination. The seeds should be sown as fresh as possible in a compost containing sieved leafmould, peat, sharp sand and acid loam. Success has been reported (Starling 1982) from sowing on sphagnum moss: although there is little resemblance to conditions in the wild habitat, the naturally high rainfall there means that there is often moss (not sphagnum) present. Seed pots should be kept in a shaded cold frame. Vegetative propagation is more reliable than seeds, either by division of rooted pieces from established plants in late winter, or by detaching single shoots to treat as cuttings in summer.

Key to the genus Shortia

la Flowers solitary, corolla broadly bell-shaped---2
b Flowers generally 2 or more per stem, corolla narrowly bell-shaped---9

2a Leaves elliptic; flowers white---6. S. sinensis
b Leaves rounded---3

3a Flowers usually white; stamens short, not exserted---4
b Flowers usually pink; stamens well exserted---6

4a Corolla 1. 5 to 2. 5 cm wide, white or pale pink; staminodes ovate; bracts confined to top of stem---1. S. galacifolia
b Corolla less than 1.5 cm wide, white; staminodes linear or absent, bracts scattered along stem---5

5a Staminodes present---4. S. rotundifolia
b Staminodes absent---5. S. exappendiculata

6a Flowers 3 to 3.5 cm wide, pale pink; anthers about equalling filaments---3. S. x intertexta
b Flowers 2.5 to 3.5 cm, rosy pink; anthers much shorter than filaments---7

7a Largest mature leaves < 3 cm long, bases cordate---2b S. uniflora var. kantoensis
b Largest mature leaves mostly 4 to 6 cm--- 8

8a Leaf bases cordate---2a. S. uniflora var. uniflora
b Leaf bases rounded or broadly cuneate---2c. S. uniflora var. orbicularis

9a Leaves mostly 4 to 12 cm long, margins with more than 7 distinct teeth---10
b Leaves 0. 5 to 5 cm long, teeth less than 8 per margin---12

10a Leaves 3.5 to 7 cm, ovate, with 5 to 10 prominent triangular acute, teeth on each margin; flowers usually white---7e. S. soldanelloides var. intercedens
b Leaf margins with smaller or more numerous low teeth flowers usually pink---11

11a Leaves 3 to 8 cm long---7. S. soldanelloides var. soldanelloides
b Leaves 8 to 12 cm long---7c. S. soldanelloides var. magna

12a Plant 2 to 5 cm tall; flowers 1 to 3; leaves less than 1.5 cm, base truncate, teeth 1 to 2---7b. S. soldanelloides var. minima
b Plant 5 to 15 cm tall; flowers 2 to 6; leaves 1.5 to 5 cm, base cordate---13

13a Leaves ovate, teeth I to 5 per margin, triangular, obtuse; flowers often white---7d S. soldanelloides var. ilicifolius
b Leaves orbicular, 5 to 8 small teeth per side; flowers 1 to 3, pink---7a. S. soldanelloides f. alpina

Illustrations

See side-bar for illustrations of leaf-shapes

The species

1. S. galacifolia Torrey and Gray (the name alludes to the resemblance of the leaves to those of Galax.) Local name: Oconee bells (the plant was first recorded from Oconee County, South Carolina). Illustration: Curtis's Botanical Magazine, t.7082 (1889); Farrer, English Rock Garden 2: 360 (1919); Quarterly Bulletin of the Alpine Garden Society 23: 183 (1955).

Plant 10 to 20 cm tall. Leaves 2 to 7 cm long and wide, orbicular or very broadly elliptic, the base rounded or slightly cordate, apex often truncate, each margin with 8 to 11 low teeth; petiole 3 to 14 cm. Flower solitary, scape erect, to 20 cm, bearing near the top a few lanceolate bracts about I cm long. Calyx lobes 1 cm, ovate, obtuse or notched. Corolla openly funnel-shaped, lobed to about half way, the lobes oblong, 1.5 to 2 cm long, truncate or rounded, fringed with small rounded teeth. Colour usually white, but pale pink and 'blue' variants are recorded (the latter may have been described from pressed specimens - the pink flowers sometimes dry blue). Stamens not exserted from corolla tube, anthers about equalling filaments, incurved. Staminodes ovate, ciliate. Capsule ovoid, 5 to 7 mm.

Eastern USA, North and South Carolina and Georgia: shady banks along streams and in moist wooded ravines, flowering in March and April. Introduced to Britain in 1888 by H.J. Elwes, who received plants from Professor C. S. Sargent. Shortia galacifolia var. brevistyla Davies is sometimes listed: its status and distinctness are uncertain.

2. S. uniflora (Maximowicz) Maximowicz (Schizocodon uniflorus Maximowicz). ('one-flowered': it was the first of the solitary flowered species to be described in Schizocodon). Japanese name: Iwa-uchiwa, 'crag fan', the shape of the leaves being like the non-folding fans called uchiwa. Illustration: Curtis's Botanical Magazine t.8166 (1907); Makino, Illustrated Flora of Nippon f.785 (1942); Quarterly Bulletin of the Alpine Garden Society 23: 180 (1955).

Plant to 15 cm tall, leaves 2.5 to 7 cm long and wide, orbicular, cordate or rounded at the base, the margins with about 8 to 13 undulate teeth. Flower solitary, pale pink, on a scape bearing a few ovate bracts towards the top. Calyx lobes 8 to 12 mm long, oblong, obtuse, with several veins. Corolla broadly campanulate, lobes spreading, 1.3 to 2.8 cm long, crenately toothed or slightly incised. Stamens well exserted from corolla tube, filaments about 3 times longer than the inflexed anthers. Staminodes scale-like, incurved, on short flat stalks, papillose. Capsule 4 to 5 mm.

Japan - northern Honshu, from Kinki to Tohoku districts, growing in woods in low mountains and flowering in April and May. Introduced to Kew in 1906, purchased 'from a firm of nurserymen in Yokohama'.

In recent Japanese works, this species is often divided into 3 varieties:

2a. var. uniflora.
Mature leaves more than 3 cm long, blade orbicular, base cordate. Tohoku district (northern Honshu), apparently extending south to Shizuoka prefecture. A white form has been named f. albens Honda.

2b. var. kantoensis Yamazaki Illustration: Satake et al, Wild flowers of Japan III: pl. 2, f. 2 (1985); Toyokuni, Alpine Flowers of Japan, 288 (1988).

Stems 5 to 10 cm; leaf blade less than 3 cm long, often broader than long, base cordate; flower c.3 cm wide. Kanto district (mountains north and west of Tokyo). S. uniflora f. albiflora Makino is said to belong to this variety. A form with somewhat double flowers is f. plena Yamazaki.

2c. var. orbicularis Honda Illustration: Satake et al, Wild Flowers of Japan III: pl. 2, f. 3 (1985); Hayashi et al, Wild Flowers of Japan, 299 (1988).

Large plants with leaves more than 3 cm long, broadly elliptic, base rounded or cuneate. Central Honshu (Kinki to Hokuriku districts). Again a white form has been described, f. satomii Sugimoto. Plotting the leaf shape and size of specimens in the herbaria of Kew and Edinburgh Botanic Gardens against their distribution shows a good correlation with the distributions above, which are quoted from Satake et al. Plants grown as 'Grandiflora' (var. grandiflora invalid) probably belong to the typical variety. Illustration: Journal of The Royal Horticultural Society 93: f. 86 (1968).

3. S. x intertexta Marchant 'Wimborne' (S. galacifolia x S. uniflora). Illustration: Journal of The Royal Horticultural Society 76: fig. 198 (1951).

This alleged hybrid has rounded leaves 2.5 to 6 cm long, with 7 to 10 sinuate teeth on each margin. The scape is 5 to 10 cm tall, with a solitary pale pink flower. The calyx lobes are elliptic-oblong, obtuse. Corolla lobes about 2 cm long, stamens with filaments 1.5 x anthers. In general appearance it resembles the early, small flowered introductions of S. uniflora apart from the slightly shorter filaments.

4. S. rotundifolia (Maximowicz) Makino (Schizocodon rotundifolius Maximowicz). 'round-leaved'. Japanese name: Shima-iwa-kagami, 'island crag mirror'. Iwa-kagami is the name of S. soldanelloides. Illustration: none seen.

Plant 8 to 15 cm tall. Leaves 2 to 8 cm long and wide, orbicular, margins with 10 to 25 shallow teeth, the base abruptly narrowed into a stalk 2 to 3 cm long. Bracts and calyx lobes 5 to 8 mm, ovate. Corolla broadly bell-shaped, 1.2 to 1.5 cm long, white or pale pink, the lobes with small rounded teeth. Capsule globose, 5 mm. In the dried specimens seen, but not dissected, the corolla appears to have 5 small obtuse staminodes.

This little known species occurs rarely in forests on mountain tops in the Iriomote and Okinawa islands in southern Japan. It appears to be similar to the Taiwanese S. exappendiculata, which however, is said to lack staminodes. The latter was at first perhaps misidentified as S. rotundifolia (cf. Hayata, 1908); alternatively, both species may occur in Taiwan.

5. S. exappendiculata Hayata (includes S. ritoensis Hayata, S. subcordata Hayata and S. transalpina Hayata). 'lacking appendages' - this species has no staminodes. Illustration: Hayata, Iconographia Plantarum Formosanum 3: t.27 (1913); Iconographia Cormophytorum Sinicorum 3: 4 f.3961 (1972); Li (ed.), Flora of Taiwan 4: t. 1 (1978).

Plant 5 to 15 cm tall. Leaves long-stalked, blades 2 to 5 cm, orbicular, base rounded or slightly cordate, margins with inconspicuous apiculate teeth. Scape with a few lanceolate bracts about 6 mm long near the top. Flowers solitary, white. Calyx lobes ovate, acute. Corolla about 1 cm long and wide, the spreading lobes crenate-serrate. Anthers erect, scarcely exserted, filaments very short. Staminodes absent.

Taiwan, in mountain woodland at about 2,000 m and flowering in spring. Probably not in cultivation and unlikely to be very hardy in Britain. See comments above under S. rotundifolia.

6. S. sinensis Hemsley. 'from China': apparently the only species in mainland China. Illustration: Hooker, Icones Plantarum 27: 2624 (1899); Iconographia Cormophytorum Sinicorum 3: 3 f.3960 (1972).

Plant 10 to 15 cm tall. Leaves 6 to 13 x 3 to 6 cm, elliptic, apex usually obtuse, margins crenate-serrate, base broadly cuneate into a narrowly winged petiole about as long as the blade. Flower solitary, white. Calyx lobes and bracts narrowly ovate, often acuminate. Corolla c. 2 cm long, lobes spreading, with small rounded teeth. Stamens slightly exserted from corolla tube, anthers erect, about as long as filaments. Staminodes 5, linear.

South China, low mountains in south-east Yunnan at altitudes around 1,000 m, flowering in spring. Probably not in cultivation.

7. S. soldanelloides (Siebold & Zuccarini) Makino (Schizocodon soldanelloides Siebold & Zuccarini). 'like Soldanella': a genus in Primulaceae with similarly fringed flowers. Japanese name Iwa-kagami, 'crag mirror' the leaves are similar in shape to old metal hand mirrors; they are also often highly glossy.

Plant 2 to 30 cm tall. Leaves 0.6 to 12 cm long and wide, orbicular or ovate, margins toothed, base rounded or more often cordate, more or less long-stalked. Flowers (1) 2 to 12 in a compact raceme. Calyx lobes oblong-lanceolate. Corolla 1.5 to 2 cm long, 1 to 1.5 cm wide, narrowly funnel-shaped, the lobes deeply fringed or incised, pink or white. Stamens scarcely exserted from corolla tube, filaments about 3 times longer than anthers. Staminodes linear.

Japan, from southern Hokkaido, throughout Honshu, Shikoku and Kyushu to Yakushima at altitudes from 300 to 1,900 m.

Turrill in the Botanical Magazine says it was 'originally described from Mt. Nekodake of which the exact location has not been found.' The best-known mountain of this name is probably that near Mount Aso in Kyushu. Quite by chance I was fortunate enough to see it on the same mountain, growing under species of Miscanthus and Sasa, at about 1,300 m. This species is extremely variable and occurs in low mountain woodland in central and northern Japan, but at higher altitudes (1,500 to 1,900 m) in Kyushu and Yakushima it is found in open habitats.

The first introduction of this species to Britain is said to be that given an Award of Merit by the RHS in 1893, when exhibited by a Captain Torrens. This plant, illustrated in the Journal of Horticulture (new series) 26: 281 (1893) and later in the Botanical Magazine, is clearly a pink-flowered form of var. ilicifolia. It was introduced in 1891 'from Myanoshta', i.e., Miyanoshita in the Hakone mountains west of Tokyo. The description above covers the whole range of variation; several varieties are recognised:

var. soldanelloides Illustration: Makino, Illustrated Flora of Nippon f.783 (1942); Kitamura et al, Coloured Illustrations of Herbaceous Plants of Japan 1: pl. 70, f. 587 (1986); Hayashi et al, Wild Flowers of Japan, 300 (1988).

Leaves 3 to 6 x 3 to 5 cm, orbicular or very broadly ovate, base rounded or shallowly cordate, margins with 7 to 15 low apiculate teeth. Flowers 3 to 10, rosy pink.
Widespread in Japan. A white form was described as Schizocodon soldanelloides f. leucanthus Takeda.

7a. f. alpina (Maximowicz) Makino Schizocodon soldanelloides f. alpinus Maximowicz) Japanese name: Ko-iwa-kagami, 'small crag mirror'. Illustration: Hayashi et al, Wild Flowers of Japan, 302 (1988); Toyokuni, Alpine Flowers of Japan, 286 (1988).

Plant 5 to 10 cm tall; leaves 1.5 to 4 cm, more or less orbicular, teeth 5 to 10, inconspicuous. Flowers 1 to 5, 1.5 to 2 cm long, pink or rarely white.

This dwarf alpine phase occurs in Hokkaido and in alpine and subalpine grassland in northern Honshu; it appears to intergrade with var. soldanelloides and is doubtfully worthy of recognition.

7b. var. minima (Makino) Masamune (Shortia soldanelloides f. minima Makino; S. yakushimensis Masamune; Schizocodon soldanelloides 'Yakushimana'; Schizocodon soldanelloides var. minimus (Makino) Hara; Schizocodon ilicifolius var. minimus (Makino) Yamazaki). Japanese name: Hime-ko-iwa-kagami, '(very) dwarf crag mirror'. Illustration: Izumi, 'Yakushima Flower journey', 193 (1985); Kitamura et al, Coloured Illustrations of Herbaceous Plants of Japan 1: f. 72.4 (1986).

Plant 2 to 5 cm tall. Leaves 0.6 to 1.5 cm, usually with 1 to 3 low teeth on each margin, base truncate or rounded. Flowers 1 or 2, pink or white.
This remarkably dwarf variety grows above the tree line in Yakushima. I saw it in a half-shaded rock crevice at about 1,800 m, with deep purple leaves 7 to 9 mm wide.

7c. var. magna Makino (Schizocodon soldanelloides var. magnus (Makino) Turrill; Schizocodon magnus (Makino) Honda; Schizocodon macrophyllus (invalid)). Japanese name: o-iwa-kagami, 'great crag mirror'. Illustration: Terasaki, Nippon Shokubutsu Zufu, 355 (1933); Curtis's Botanical Magazine new series, t.110 (1950); Suzuki, Alpine Plants in Eastern Japan f.255 (1982); Hayashi et al, Wild Flowers of Japan, 301 (1988).

Plant to 20 cm tall. Leaves 8 to 12 cm long, with numerous small apiculate teeth on each margin. Flowers pink or white (Schizocodon soldanelloides var. magnus f. niveus Hara).

Ohwi states that this is from the 'western region'; however other references cite southern Hokkaido and central and northern Honshu (Sea of Japan side) as its home. Flowering from April to June.

7d. var. ilicifolia (Maximowicz) Makino (Schizocodon ilicifolius Maximowicz; Schizocodon soldanelloides var. ilicifolius (Maximowicz) Makino; Shortia ilicifolia (Maximowicz) Takeda). Japanese name: Hime-iwa-kagami, 'dwarf crag mirror'. Illustration: Curtis's Botanical Magazine t.7316 (1893) (as Schizocodon soldanelloides); Elliott, Portraits of Alpine Plants, 59 (n.d .) (as Schizocodon soldanelloides); Kitamura et al, Coloured Illustrations of Herbaceous Plants of Japan 1: pl. 70 f. 5 88 (1985); Toyokuni, Alpine Flowers of Japan, 287 (1988).

Plant 5 to 15 cm tall. Leaves 1 to 5 cm long, broadly ovate, rather angled with 2 to 5 large low blunt or apiculate teeth on each margin. Flowers (1) 2 to 5, white or pink (Schizocodon ilicifolius f. purpureiflorus Takeda). Kanto area north and west of Tokyo including the Hakone mountains, in woodland, often forming extensive colonies 2 to 3 m wide. Flowers in April to July. In spite of the name, the mature leaves are only bluntly toothed. Plants sold as Askival Strain appear to belong here - those seen have rather ovate leaves and small, deep pink flowers.

7e. var. intercedens Ohwi (Schizocodon intercedens (Ohwi) Yamazaki; Schizocodon ilicifolius var. intercedens (Ohwi) Yamazaki). Japanese name: Yama-iwa-kagami, 'mountain crag mirror'. Illustration: Quarterly Bulletin of the Alpine Garden Society 50: 323 (1982); Satake et al, Wild Flowers of Japan III: pl. 2, f.5 (1985); Hayashi et al, Wild Flowers of Japan, 302 (1988).

Plant 10 to 20 cm tall. Leaves to 7 x 4 cm, broadly ovate, obtuse, base cordate; each margin with 5 to 15 coarse, sharp teeth; venation rather distinctly reticulate above. Flowers 3 to 7, white or rarely pink.

Tokaido district in south-east Japan, in woodland in low mountains.

RHS Awards

Not surprisingly there have been several awards, both Award of Merit and First Class Certificate, over the years.

S. galacifolia: FCC (Elwes) 1889.
S. x intertexta 'Wimborne': AM (Marchant) 1951
S. uniflora: AM (Wallace) 1908. 'Grandiflora': FCC (Marchant) 1935 'Grandiflora Rubens': AM (Marchant) 1938 ('a lovely rose-pink'). 'Snowflake': AM (Marchant) 1940 ('extra large white flowers').
S. soldanelloides: FCC (Torrens) 1893 - apparently var. ilicifolia (pink). var. ilicifolia (white): AM (Stoker) 1935. var. magna: FCC (Marchant) 1938; AM (Reuthe) 1924. var. minima: PC (Edrom) 1966.

Availability

The current Plant-Finder lists the following taxa:
Shortia galacifolia; var. brevistyla.
S. x intertexta 'Wimborne'.
S. soldanelloides; Askival Strain; "dwarf form"; var. ilicifolius; var. minima.
S. uniflora; 'Grandiflora'; var. kantoensis.

Acknowledgements

I am most grateful to the following for their assistance with this article: The Director of the Royal Botanic Gardens, Kew for access to the herbarium collections; The Regius Keeper, Royal Botanic Gardens, Edinburgh, for the loan of specimens; Miss Julia Corden for providing living specimens; Miss Natsuko Kusuda for guiding me to various taxa in the wild in Japan.

References

HAYASHI, Y., C. AZEGAMI & C. HISHIYAMA. 1983. Wild Flowers of Japan. Tokyo
HAYATA, B. 1908. Flora Montana Formosae. Joumal of the College of Science of the Imperial University of Tokyo, Vol. 25, pp. 1-260.
KITAMURA, S., G. MURATA & M. HORI. 1986. Coloured Illustrations of Herbaceous Plants of Japan (1). Osaka.
LI, HUI-LIN. 1978. Flora of Taiwan. Taipei.
MABBERLEY, D.J. 1988. The Plant Book. Cambridge.
MAKINO, T. 1942. An Illustrated Flora of Nippon. Tokyo.
OHWI, J. 1965. Flora of Japan (in English). Washington.
PHILIP, CHRIS. 1989. The Plant-Finder. Ashbourne.
SATAKE, Y., J. OHWI, S. KITAMURA, S. KAKINORI and T. TOMINARI, 1985. Wild Flowers of Japan. Tokyo.
SCOTT, P.J. & R.T. DAY. 1983. Diapensiaceae: a review of the taxonomy. Taxon, 32: pp.417-423.
STARLING, B.N. 1982. Shortia soldanelloides var. intercedens. Quarterly Bulletin of the Alpine Garden Society, 50:, pp. 323.
TOYOKUNI, H. 1988. Alpine Plants of Japan. Tokyo.
WALKER, E.H. 1976. Flora of Okinawa and the Southern Ryukyu Islands. Washington.

This article was first published in The Plantsman 12(1): 23-34 (1990)