Tropicos | Name - !Lapeirousia Pourr.

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Iridaceae in sub-Saharan Africa

African Iridaceae > Iridaceae > Lapeirousia

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!Lapeirousia Pourr.

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Project Name Data (Last Modified On 6/6/2016)

Acceptance : Accepted

Taxon Profile (Last Modified On 6/16/2016)

Description: Deciduous geophytes. Corms bell-shaped with flat base, rooting from lower edges; axillary in origin; tunics of hard, woody layers, sometimes spiny at base. Foliage leaves few, lowermost linear to sword-shaped, inserted on stem near ground level, closely corrugate, upper leaves progressively smaller. Stem aerial or sometimes subterranean, compressed, often and angled, angles sometimes winged, simple or branched. Inflorescence a spike or when acaulescent, a dense rosette; bracts paired and opposed, outer green and firm to ± succulent, sometimes ridged, keeled, crisped or toothed; inner much shorter, usually hidden by outer, 2-keeled and often partly membranous, forked at apex. Flowers zygomorphic or actinomorphic in acaulescent species, often salver-shaped, blue, purple, red, pink or white, lower or all tepals usually with contrasting darker or lighter markings, sometimes sweetly scented; perianth tube cylindric or obliquely funnel-shaped, short to extremely long; tepals subequal or unequal, with dorsal largest. Stamens unilateral and arcuate or symmetrically disposed; filaments slender, free; anthers linear, splitting longitudinally. Ovary ± ovoid; style filiform, 3-branched, style branches usually forked for ± 1/2 their length, occasionally not divided. Capsules ovoid to oblong, cartilaginous, often showing outline of seeds. Seeds globose, flattened at chalazal end, either smooth with surface cells domed (rarely tuberculate) or rugulo-reticulate or reticulate with surface cell walls flat. Basic chromosome number x = 9; diploid numbers 2n = 18, 16.

Etymology: named in honour of the Compte de la Peyrouse, 18th century patron of French science and contemporary of the Abbe Pourret, author of the genus.

General Notes: Species 27; mainly in winter-rainfall western South Africa and southwestern Namibia, also central South Africa, Botswana and south tropical Africa, mainly in sandy soils or rock outcrops.

Molecular phylogenetic study has resulted in a narrower circumscription of Lapeirousia than maintained until 2015 and the removal from the genus of the tropical and eastern southern African species to Afrosolen (syn. Psilosiphon), and several Cape species to Codonorhiza. Lapeirousia now includes species with spicate inflorescences (unless acaulescent), large fleshy, unequal outer and inner floral bracts, and corms either bell- or obconic corms with hard, woody tunics. Unlike Codonorhiza and Schizorhiza the pollen grains have a 2-banded operculum and the basic chromosome numbers, x = 9 or 8 departs from that in these two genera.

Florally Lapeirousia species are strikingly diverse in floral morphology and included species with short to extremely long perianth tubes and perianth colours of white to pink, intense violet or red, then with white markings on the klower tepals. L. odoratissima has the longest perianth tube in the genus, up to 140 mm long, the scented, white flowers are adapted for pollination by long-proboscid hawk moths. Species with deeply pigmented but unscented flowers with tubes of intermediate length are pollinated by long-probosid nemestrinid flies. Speciation in the genus has been associated with repeated shifts in pollination system. Several species, among them L. plicata and L. odoratissima have underground stems, the flowers than crowded together in a basal cluster or rosette. The genus has its greatest diversity on western southern Africa, centered in Namaqualand and adjacent Western Cape and the western Karoo of Northern Cape.

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1	Plants tufted, ± acaulescent with axis contracted above ground level and inflorescence congested; flowers radially symmetric	(2)
+	Plants with aerial stems unless depauperate (e.g. L. exilis, L. arenicola); flowers zygomorphic with stamens unilateral	(7)

2 (1)	Floral bracts 60–150 mm long; perianth tube 100–140 mm long	Lapeirousia odoratissima
+	Floral bracts 40–50 mm long; perianth tube 12–60 mm long	(3)

3 (2)	Flowers violet, lower 1/3 of tepals dark violet to black with wedge-shaped white mark in centre of dark zone; perianth tube 50–60 mm long	Lapeirousia oreogena
+	Flowers whitish or pale blue, sometimes with dark blue to purple mark near base of tepals; perianth tube 12–50 mm long	(4)

4 (3)	Perianth tube 12–30 mm long; tepals 7–9 mm long; anthers 1.8–3 mm long, blue or whitish	Lapeirousia plicata
+	Perianth tube (33–)35–60 mm long; tepals 10–12 mm long; anthers 3–4 mm long, white or pale yellow	(5)

5 (4)	Flowers ± white; leafy upper parts of floral bracts ± straight, channelled to apex, not ribbed	Lapeirousia kalahariensis
+	Flowers white or pale blue; leafy upper parts of floral bracts falcate, unifacial above and strongly ribbed	Lapeirousia montana

6	Flowers predominantly white to creamy white, often flushed pink outside; perianth tube 7–15 mm long	(7)
+	Flowers variously coloured; perianth tube 20–70 mm long	(10)

7 (1)	Corm bell-shaped, basal rim minutely serrated or entire and lobed	(8)
+	Corm obconic (triangular in profile), basal rim bearing prominent, spreading spines	(9)

8 (7)	Perianth tube 7–10 mm long, obliquely funnel-shaped; corm margin with short fine teeth directed downward; plants of the Cedarberg, Gifberg and Bokkeveld Mtns	Lapeirousia divaricata
+	Perianth tube 13–15 mm long, ± slender throughout; corm margins entire; plants of the Knersvlakte	Lapeirousia angustifolia

9 (7)	Dorsal tepal 18–23 × 5–8 mm	Lapeirousia spinosa
+	Dorsal tepal 9–11 × 2–3 mm	Lapeirousia tenuis

10 (6)	Corm bell-shaped, basal rim bluntly ridged to crenate or minutely serrate with teeth directed downward	(11)
+	Corm obconic (triangular in profile) with margins bearing prominent, spreading spines	(22)

11 (10)	Outer floral bracts obtuse to retuse when opened flat	Lapeirousia pyramidalis
+	Outer floral bracts tapering to an acute apex	(12)

12 (11)	Flowers deep violet or cherry-red to magenta, lower tepals with white to yellow markings near base	(13)
+	Flowers not as above	(14)

13 (12)	Floral bracts with median keel, without white patches; flowers cherry-red to magenta; perianth tube 40–55 mm long	Lapeirousia silenoides
+	Most or all floral bracts 2-keeled, fenestrate with white patches; flowers violet to purple, lower tepals streaked with white; perianth tube 30–40 mm long	Lapeirousia jacquinii

14 (12)	Outer floral bracts mostly 6–10 mm long; lower tepals ± linear to narrowly lanceolate with a short, filiform tooth near base	Lapeirousia anceps
+	Outer floral bracts (10–)12–25 mm long; lower tepals broadly lanceolate to ovate, with or without teeth	(15)

15 (14)	Perianth white to pink, pale blue or maroon-brown, not marked with red on lower tepals	(16)
+	Perianth white to pink or creamy beige, lower tepals always marked with red to brown near base	(19)

16 (15)	Perianth tube slender below, ± abruptly expanded to wider upper part; tepals ascending below to form part of floral cup, spreading distally; tepals predominantly pink to lilac with yellow nectar guides on lower tepals; style dividing opposite or beyond anther tips	Lapeirousia barklyi
+	Perianth tube slender ± throughout, slightly wider distally; tepals spreading from base; tepals predominantly white to ivory or pale blue; style dividing between base and middle of anthers	(17)

17 (16)	Plants slender, less than 60 mm high, often unbranched; flowers pale blue (rarely ± white) with violet streaks on lower tepals	Lapeirousia exilis
+	Plants usually > 100 mm high, usually repeatedly branched from base; flowers white, pale yellow, yellow-brown or dull maroon, usually without contrasting markings on lower tepals	(18)

18 (17)	Perianth tube 28–35 mm long; tepals 13–15 × 2–3 mm; bracts (12–)15–20(–25) mm long	Lapeirousia littoralis
+	Perianth tube (25–)30–45(–70) mm long; tepals 18–30 × 1.3–2 mm; bracts 10–18(–23) mm long	Lapeirousia caudata

19 (15)	Perianth tube 40–55 mm long; corm with basal margins entire to crenately lobed	Lapeirousia verecunda
+	Perianth tube (10–)12– 35 mm long; corm with basal margins minutely serrated	(20)

20 (19)	Lower tepals ± 13 × 5 mm	Lapeirousia macrospatha
+	Lower tepals 8–11 × 3–4 mm	(21)

21 (20)	Corm relatively shallowly buried, and underground part of stem not bearing cormlets at nodes; perianth tube mostly 15–25 mm long	Lapeirousia arenicola
+	Corm relatively deeply seated, with underground part of stem bearing cormlets at nodes; perianth tube mostly 27–35 mm long	Lapeirousia simulans

22 (10)	Flowers white to beige or blue-mauve (rarely pink), usually with red markings on lower tepals	(23)
+	Flowers predominantly blue, violet, purple or magenta, variously marked on lower tepals	(24)

23 (22)	Perianth tube slender below, expanded in upper 5–10 mm into a wider gullet; style dividing opposite base to upper 1/3 of anthers; basal leaf smooth	Lapeirousia fabricii
+	Perianth tube slender, ± uniformly wide throughout; tepals spreading from base; lower tepals not bearing a tooth at base; style dividing opposite or above anther tepals; basal leaf sparsely hairy	Lapeirousia kamiesmontana

24 (22)	All or only median lower tepal with tooth-like projection near base	(25)
+	All lower tepals without tooth-like projections	(26)

25 (24)	Only lower median tepal with tooth near base; upper lateral tepals strongly recurved; lower tepals with white V-shaped mark near base on darker violet background	Lapeirousia kamiesmontana
+	All three lower tepals with tooth near base; upper lateral tepals not obviously recurved; lower tepals white near base with large red to purple blotch in centre	Lapeirousia violacea

26 (24)	Basal leaf smooth or minutely papillate along edges of ribs; perianth tube (25–)35–45 mm long; perianth pale to deep blue to violet, lower tepals white(–pale yellow) at base	Lapeirousia dolomitica
+	Basal leaf sparsely hairy; perianth tube 40–50 mm long; perianth deep magenta to purple marked with white lines on lower margins and darker magenta in lower midline	Lapeirousia lewisiana