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Published In: Index Sem. Horto Bot. Berol. 1854 App.: 10. 1855. (Index Sem. Horto Bot. Berol.) Name publication detail
 

Project Name Data (Last Modified On 6/6/2016)
Acceptance : Accepted
Taxon Profile     (Last Modified On 12/14/2016)
Description: Evergreen or rarely deciduous perennials, solitary or growing in clumps. Rootstock a depressed-globose corm rooting from below and axial in origin, persisting; tunics of coarse, netted fibres, often accumulating in a dense mass. Stem aerial, slender and wiry, often drooping above, rarely erect, usually several-branched, subtending bracts dry and thread-like. Leaves several, often without a definite midrib in mature plants , plane, linear, leathery and fibrotic; with marginal vascular bundle and unspecialized epidermal cells. Spikes pendent or erect spike, axes wiry; bracts dry, usually papery and translucent, occasionally solid and herbaceous or leathery in centre or lower part, becoming torn above, usually brown-streaked or -spotted, outer with prominent main vein and numerous smaller lateral veins, acute or attenuate, inner smaller than outer, 2-veined, forked apically. Flowers actinomorphic, bell-shaped, long-lived, usually nodding, mostly pink to mauve but also maroon or purple, yellow or white, with dark markings near tepal bases, unscented, with nectar from septal nectaries; perianth tube funnel-shaped, relatively short; tepals subequal, cupped or spreading distally, often enclosing stamens and style. Stamens symmetrically disposed, central; filaments slender; anthers linear, dehiscing longitudinally. Ovary globose, sessile; style filiform, surrounded by stamens, usually included in floral cup, branches short, slender, slightly expanded above and recurved. Capsules globose, cartilaginous; seeds globose or lightly angled, flattened at the chalazal end, smooth, hard, often shiny,  ovular vascular trace excluded. Pollen monosulcate-operculate, operculum 2-banded, exine perforate-scabrate. Basic chromosome number x = 10.
Etymology: from the Greek, dierama, a funnel, describing the shape of the flower.
Revisionary account:
General Notes: Species ± 45, southern and eastern tropical Africa, centred in eastern southern Africa with 37 species in the region, and six species restricted to tropical Africa from Zimbabwe through Malawi, Tanzania and Kenya to Ethiopia; mainly montane but also coastal in South Africa, favoring rocky grassland but also in marshes and along streams. Primarily a genus of highland grassland but extending to near the coast along the temperate eastern seaboard of South Africa, most diverse in KwaZulu-Natal with 26 species (Hilliard & Burtt, 1991).

Dierama is recognized by the mostly evergreen habit, tough, fibrous leaves, and slender, wiry stems with drooping spikes of radially symmetric, funnel-shaped flowers subtended by large, dry, papery or sometimes partly herbaceous floral bracts, generally pale with brown streaks and veins. A few species are exceptional in having semi-erect spikes with nearly upright flowers. The adult leaves are distinctive in lacking a prominent central vein, this present in juveniles.

Dierama is one a small group of allied genera with more or less dry floral bracts and specialized seeds with a smooth, glossy testa and a vascular bundle that is excluded from the seed body during development. Within this group it is most closely allied to Tritonia and Ixia, where the unusually flexible, wiry stems, ancestrally actinomorphic flowers, and basic chromosome number x = 10 suggest a likely sister relationship with Ixia, which is evidently derived in possessing 3-veined and often tricuspidate outer bracts, and pollen with a 1-banded operculum.

The flowers are pollinated by solitary bees that forage for nectar and pollen. The genus shows only modest floral variation, confined to size, colour and degree of spreading of the tepals.

Almost all the species merit horticultural attention, but few are available in the trade, where they are often misidentified as D. pendulum, for many years the only named species.

The taxonomy of Dierama is still far from adequately understood despite the monograph by Hilliard & Burtt (1991). Many of the taxa recognized at species level by Hilliard & Burtt (1991) were considered by them to have ‘multiple relationships with one another’, and more work is clearly required to analyse this further. As it is, species recognition in the genus is difficult, both because of the lack of critical diagnostic features and the frequent introgression between species. The following identification key serves to discriminate typical examples. The original keys to the species provided by Hilliard & Burtt (1991) should also be consulted


 

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1 Plants of southern Africa (South Africa, Lesotho and Swaziland (2)
+ Plants of eastern tropical Africa (Zimbabwe and Mozambique north to Ethiopia) (39)
2 (1) Foliage leaves produced on separate shoot alongside flowering stem and often not fully formed at flowering; plants flowering early spring, August to September (3)
+ Foliage leaves produced at base of flowering stem and fully formed at flowering; plants flowering in spring and summer, September to February or later (4)
3 (2) Flowering stem lacking conspicuous basal internode and without axillary cormlets; tepals suberect, flaring distally, ± twice as long as perianth tube Plants solitary or few in small tufts, with pendulous inflorescences; leaves 2–6 mm wide; co-florescences 2 to 5; flowers funnel- or bell-shaped Dierama nixonianum
+ Flowering stem with conspicuous basal internode and with axillary cormlets in lowermost leaf axil; tepals spreading wodely from near base, ± three times as long as perianth tube Dierama trichorhizum
4 (2) Bracts with solid patch of hard tissue in lower 1/2 to 2/3, this often drying pale buff or uniform brown (5)
+ Bracts membranous or with solid patch of tissue only at extreme base (6)
5 (4) Plants solitary or few in small tufts, with pendulous inflorescences; leaves 2–6 mm wide; co-florescences 2 to 5; flowers funnel- or bell-shaped Dierama insigne
+ Plants forming large clumps with erect or suberect inflorescences; leaves 6–12 mm wide; co-florescences ± 10; flowers subrotate Dierama erectum
6 (4) Inflorescences erect and suberect; bracts whitish to orange-buff and lightly flecked all over (7)
+ Inflorescences ± pendulous; bracts various (8)
7 (6) Flowering stems 1 000–1 500 mm tall; leaves 450–1 000 mm long; lateral spikes mostly 6 to 13-flowered; perianth tube mostly 6–8 mm long; plants from central KwaZulu-Natal to Mpumalanga Dierama galpinii
+ Flowering stems 450–850 mm tall; leaves 300–600 mm long; lteral spikes mostly 4 to 7-flowered; perianth tube mostly 5–6 mm long; plants from southern KwaZulu-Natal Dierama tysonii
8 (6) Bracts entirely white or so lightly flecked as to appear white (9)
+ Bracts ± evidently flecked with brown (14)
9 (8) Flowers white to pale yellow, rarely pale pink (10)
+ Flowers pink to purple (12)
10 (9) Terminal spike 3 to 6-flowered; bracts 24–32 mm long; perianth 30–50 mm long Dierama luteoalbidum
+ Terminal spike mostly 6 to 12-flowered; bracts 14–25 mm long; perianth 13–30(–35) mm long (11)
11 (10) Perianth 18–35 mm long Dierama argyreum
+ Perainth 15–18 mm long Dierama pallidum
12 (9) Perianth 14–18 mm long, often shorter than the bracts; anthers 5–6 mm long Dierama dubium
+ Perianth (17–)20–33 mm long, much longer than the bracts; anthers 7–10 mm long (13)
13 (12) Flowering stems solitary or up to three in small tufts; leaves 3–6 mm wide; flowers deep red-purple Dierama reynoldsii
+ Flowering stems forming large clumps; leaves (5–)6–15 mm wide; flower mostly pale pink, rarely deep pink to purple Dierama latifolium
14 (8) Flowers white to pale yellow (15)
+ Flowers pink to purple or dark wine-red (17)
15 (14) Leaves almost needle-like, 1–2.5 mm wide; bracts heavily flecked and almost solidly coloured throughout except along margins Dierama pumilum
+ Leaves 3–9 mm wide; bracts moderately to heavily flecked toward base with paler shoulders (16)
16 (15) Anthers 5–7 mm long; plants of KwaZulu-Natal Dierama sertum
+ Anthers 7–9 mm long; plants from Swaziland Dierama elatum
17 (14) Flowers dark red-purple, rarely purple but then perianth less than 35 mm long (18)
+ Flowers pale to deep pink or mauve, rarely purple but then perianth 35–54 mm long (21)
18 (17) Perianth 22–31 mm long (19)
+ Perianth 15–23 mm long (20)
19 (18) Plants 1 200–2 100 mm high; terminal spike 8 to 18-flowered; plants from Mpumalanga to Northern KwaZulu-Natal Dierama tyrium
+ Plants 750–1 250 mm high; terminal spike mostly 4 to 8-flowered; plants from Eastern Cape Dierama atrum
20 (18) Bracts reddish brown with paler shoulders, with 4 or 5 main veins each side of the midvein; lateral spikes often borne on strikingly long peduncles, usually 90–230 mm long Dierama mobile
+ Bracts dark brown with sharply contrasting white shoulders, with 6 to 8 main veins each side of the midvein; lateral spikes on shorter peduncles 60–125 mm long Dierama pictum
21 (17) Small, mostly clump-forming plants 300–600 mm tall with leaves 1–4 mm wide; terminal spike 1 to 4(5)-flowered; bracts bright rusty brown with 6 to 8 main veins each side of the midvein; flowers bright pink or reddish Dierama pauciflorum
+ Not as above (22)
22 (21) Flowering stems forming large clumps; perianth 15.5–20.5 mm long with stigmas held 3.5–7.5 mm below top Dierama floriferum
+ Not as above (23)
23 (22) from Western and Eastern Cape, Free State or southern and central KwaZulu-Natal (24)
+ Plants from northern KwaZulu-Natal, Gauteng, Mpumalanga, Limpopo or Swaziland (33)
24 (23) Perianth 28–50 mm long and plants from west of the Kei River (25)
+ Perianth up to 30(–35) mm long and plants from east of the Kei River (28)
25 (24) Tips of tepals ± folded together and twisted giving them a pointed appearance Dierama grandiflorum
+ Tips of tepals not folded and twisted (26)
26 (25) Flowers funnel-shaped with widely flaring tepals; plants from west of Grahamstown Dierama pendulum
+ Flowers ovoid in shape with suberect or weakly spreading tepals; plants from east of Grahamstown Dierama pulcherrimum
27 Perianth mostly 26–35 mm long with tube 8–13 mm long; anthers mostly 8–12 mm long Dierama robustum
+ Perianth mostly 15–28 mm long with tube 5–8 mm long; anthers 5–8 mm long (28)
28 (24) Main veins 6 to 9 each side of the midvein with well developed intermediate veins, all coalescing to form a solid base Dierama ambiguum
+ veins 4 to 6 each side of the midvein, intermediates well developed or not but never coalescing (29)
29 (28) Plants forming clumps (30)
+ Plants solitary or few in tufts (31)
30 (29) Flowers pale mauve; perianth 25–28 mm long with tepals 8–12 mm wide Dierama jucundum
+ Flowers mostly pink to red, rarely mauve; perianth up to 23 mm long with tepals 5–8 mm wide (31)
31 (29) Bracts two internodes long, with 6 main veins on each side of the midvein, all veins closely contiguous and parallel Dierama cooperi
+ Bracts usually shorter than two internodes long, with 4 to 6 main veins on each side of the midvein, all veins not closely contiguous and parallel (32)
32 (31) Flowers pale pink or almost white; bracts drab; plants coastal from Durban southward Dierama igneum
+ Flowers and bracts more richly coloured; plants from Drakensberg foothills and lower slopes Dierama dissimile
33 (23) Perianth 26–37 mm long with tube (6.5–)8–12 mm long; leaves (4–)6–10 mm wide Dierama formosum
+ Perianth 13-25(–27) mm long with tube 4–7,5 mm long; leaves 1.5–5.0 mm wide (34)
34 (33) Bracts with 6 to 8 main veins each side of midvein (35)
+ Bracts with 3 to 5 main veins each side of midvein (36)
35 (34) Bracts dark brown with contrasting white shoulders; perianth pink to wine-red, 15–23 mm long Dierama pictum
+ Bracts chestnut brown with paler brown shoulders; perianth pink, 20–29 mm long Dierama nebrownii
36 (34) Lateral spikes 6 to 8 Dierama adelphicum
+ Lateral spikes mostly up to 5 (37)
37 (36) Bracts delicately veined, with 3 or 4 faint main veins restricted to basal half Dierama gracile
+ Bracts more strongly and heavily veined (38)
38 (37) Bracts < 2 internodes long; perianth mostly 19–25 mm long; anthers mostly 6–7 mm long Dierama mossii
+ Bracts 2 internodes long or longer; perianth mostly 13–18 mm long; anthers mostly 4.5–6.0 mm long Dierama medium
39 (1) Plants single stemmed or 414forming small clumps; spikes erect Dierama plowesii
+ Plants single stemmed or forming small to large clumps; spikes pendulous (40)
40 (39) Bracts with a solid patch of hard tissue at least in the lower part, this often drying a uniform pale buff or brown (41)
+ Bracts without a solid patch of hard tissue but veins often closely set (41)
41 (40) Flowers 32--45 mm long; perianth tube 10--15 mm long; style branches held 8--16 mm below tepal tips Dierama inyangense
+ Flowers 20--29 mm long; perianth tube 6.5-- 10 mm long; style branches held 2.5--6.5 mm below tepal tips Dierama densiflorum
42 Plants forming large clumps of several stems (43)
+ Plants solitary or in small clumps of few stems (45)
43 (42) Floral bracts rich rusty brown with 6--8veinseach side of main vein and fading out in upper third; leaves 2--4 mm wide Dierama pauciflorum
+ Floral bracts either not or with fewer veins or leaves broader (44)
44 (43) Floral bracts less than 2 internodes long; terminal spike 2--6-flowered Dierama cupuliflorum
+ Floral bracts 2 internodes long or longer; terminal spike 6--10-flowered Dierama formosum
45 (42) Terminal spike 1--3(--5)-flowered; style reaching (6--)9--15 mm. below tepal apices Dierama pauciflorum
+ Combination of characters not as above (terminal spike with more flowers or floral bracts not bright rust brown or leaves broader (46)
46 (45) Flowers 22--32 mm long; tepals 15--22 x 6--11 mm; foliage leaves borne on flowering stem Dierama longistylum
+ Flowers 17--22 mm long; tepals 10--15 x 5--7 mm; foliage leaves borne on separate shoots Dierama parviflorum
 

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