Tropicos | Name - !!Watsonia Mill.

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Iridaceae in sub-Saharan Africa

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!!Watsonia Mill.

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

Acceptance : Accepted

Taxon Profile (Last Modified On 8/9/2016)

Description: Deciduous or sometimes evergreen perennials. Corm depressed-globose, axillary in origin, old corms often not resorbed, tunics leathery becoming fibrous and netted with age. Cataphylls 2 or 3, dry and papery or leathery. Leaves several, foliage leaves mostly in a basal fan, lanceolate to linear, leathery and fibrotic, plane with main vein and margins often thickened and prominent, cauline leaves smaller, inserted on upper 1/2 of stem, entirely sheathing and bract-like; marginal vascular bundle present, epidermis unspecialized. Stem aerial, simple or with one to several short, ascending branches, subterete. Inflorescence a 2-ranked spike; bracts firm-textured, partly to completely dry at anthesis, inner shorter to longer than outer, 2-nerved, usually forked apically. Flowers zygomorphic (radially symmetric in W. marginata), long-lived, pink, orange or red, rarely cream to pale yellow, sometimes with darker markings on lower tepals, unscented or rarely lightly scented, with nectar from septal nectaries; perianth tube slightly to strongly curved, lower part narrowly cylindric, upper part flared or broadly cylindric; tepals subequal, ± spreading or dorsal horizontal. Stamens unilateral and arcuate or sometimes deflexed, rarely central and symmetrically disposed; filaments inserted well below top of perianth tube at junction between lower and upper parts. Ovary ovoid; style filiform, 3-branched distally, branches slender and forked for half their length. Capsules globose to oblong or elongate, sometimes spindle-shaped, leathery to woody, tardily dehiscent. Seeds large, angular or compressed and winged at chalazal end or at both ends, areolate, matte. Pollen monosulcate-operculate, operculum 2-banded; exine perforate-scabrate. Basic chromosome number x = 9.

Etymology: named in honour of the eighteenth century British botanist, William Watson.

Revisionary account:

General Notes: Species 53, southern Africa, centred in the southwestern parts of Western Cape but extending north into Namaqualand, and east into the summer rainfall zone of eastern South Africa, Swaziland, and Lesotho.

Watsonia can be recognized by its basal fan of leathery leaves often with thickened main vein and margins and the sturdy, erect, 2-ranked spike, often with numerous closely packed flowers subtended by firm, leathery bracts. The flowers are usually quite large, mostly pink to orange or red to purple, rarely pale yellow, with slender style branches divided for half their length. The large, somewhat flattened corms are axillary in origin, and the leaves have the ancestral marginal anatomy type, with a marginal vein with phloem cap. Watsonia has a unique basic chromosome number in the subfamily, x = 9, and a karyotype with one large pair of chromosomes. Seeds of many species are specialized in having the proximal and distal ends flattened and drawn into wing-like processes. In a few species the seeds may have only one large distal wing. Winged seeds are found only in species of the southern African winter-rainfall zone and it is here that the species diversity is greatest.

Flower colour is closely correlated with perianth shape and pollination system. Pink or pale yellow flowers, with either a relatively short, flared tube or a moderately long, slender tube are adapted for pollination by bees or long-proboscid flies, whereas red or orange flowers, nearly always with a perianth tube that is narrow below and wide and tubular above, are pollinated by sunbirds.

The relationships of Watsonia lie with the other genera of Crocoideae with similar, deeply divided style branches and axillary corm development, together comprising tribe Watsonieae. Within the tribe, Watsonia is sister to Pillansia, which has radially symmetric, orange flowers and large, areolate seeds but with a very different leaf and inflorescence structure. Basic chromosome number for the tribe is evidently x = 10, and Watsonia appears derived in its secondary base of x = 9.

The existing classification of the genus is largely intuitive and is based on proposed morphological specializations (Goldblatt, 1989). Watsonia marginata was segregated as the monospecific subg. Neuberia for its unique, actinomorphic flowers, which have been interpreted as plesiomorphic. The remaining species are segregated in three sections in subg. Watsonia. Outgroup comparison now suggests that the actinomorphic flower is secondarily derived in the genus. In the absence of corroborative phylogenetic data.

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1	Species of summer rainfall eastern southern Africa (Port Elizabeth to Limpopo)	(2)
+	Species of winter rainfall western southern Africa (Namaqualand to Port Elizabeth)	(25)

2 (1)	Upper part of perianth tube above stamen insertion ± cylindric, barely wider at mouth than near middle of upper part; tepals usually shorter than to ± as long as upper part of tube; filaments usually well exserted, 7–15 mm from tube, rarely less; flowers usually red to orange, or pink to purple	(3)
+	Upper part of perianth tube above stamen insertion flared evenly from base to apex, usually ± twice as wide at mouth as near centre; tepals usually 1.5–2.0 times as long as upper part of tube; filaments included or shortly exserted up to 5 mm from tube; flowers usually pink to purple, rarely red, white or yellow	(9)

3 (2)	Floral bracts short, 5–14(–16) mm long (disregard lower 1–3 flowers)	(4)
+	Floral bracts longer, 15–45 mm long	(6)

4 (3)	Filaments 10–20 mm long, included in perianth tube or exserted up to 5 mm	Watsonia bachmannii
+	Filaments 25–45 mm long, well exserted from perianth tube	(5)

5 (4)	Filaments 16–28 mm long; flowers pink to purple or rarely red; tepals 8–15 mm wide; capsules narrowly obovoid	Watsonia knysnana
+	Filaments 30–38 mm long; flowers scarlet to dark red; tepals 4–10 mm wide; capsules elongate-fusiform	Watsonia angusta

6 (3)	Inner (broader) tepals at least 10 mm wide and at least half as wide as long	(7)
+	Inner (broader) tepals 4.5–9.0 mm wide and more than twice as long as wide	(8)

7 (6)	Flowers pink to purple; filaments 16–25(–30) mm long	Watsonia knysnana
+	Flowers orange to red; filaments (25–)30–45 mm long	Watsonia pillansii

8 (6)	Leaves 30–60 mm wide; bracts green below; plants from northern KwaZulu-Natal to Mpumalanga	Watsonia latifolia
+	Leaves 3–25 mm wide; bracts entirely dry and brown; plants from southern KwaZulu-Natal to Eastern Cape	Watsonia gladioloides

9 (2)	Lower part of perianth tube 30–55 mm long	(10)
+	Lower part of perianth tube 7–25 mm long	(11)

10 (9)	Bracts dry and brown above, 25–35 mm long; upper part of perianth tube ± 15 mm long; spike 15- or more-flowered	Watsonia wilmsii
+	Bracts herbaceous, 33–55 mm long; upper part of perianth tube ± 6 mm long; spike 3- to 7-flowered	Watsonia occulta

11 (9)	Flowers pale yellow to cream, rarely maroon, small, tepals 10–18 mm long; basal leaves 1 or 2, linear, 3–6 mm wide, with heavily thickened midrib and margins	Watsonia watsonioides
+	Flowers usually pink to purple or red, rarely white, usually larger; basal leaves usually 3 or more, 2–80 mm wide, with or without heavily thickened midrib and margins	(12)

12 (11)	Bracts entirely dry at flowering, uniformly brown or with pale veins, (10–)20–40 mm long, strongly overlapping and at least 2 internodes long; spike crowded with (10)20 to 60 flowers	(13)
+	Bracts usually partly green and herbaceous below, 5–30 mm long, sometimes overlapping but then either shorter than 2 internodes long or green below; spike relatively lax and with 3 to 30 flowers	(17)

13 (12)	Plants solitary with erect stems	(14)
+	Plants forming clumps, with stems ± erect or inclined below	(15)

14 (13)	Leaves channelled with margins curved inward; bract-like cauline leaves not or hardly inflated	Watsonia canaliculata
+	Leaves plane, the lower usually dead and dry at flowering; bract-like cauline leaves inflated	Watsonia lepida

15 (13)	Spike internodes (7–)9–15 mm long; tepals 25–32 mm long; spike 15- to 30-flowered	Watsonia confusa
+	Spike internodes 4–8 mm long; tepals 16–25 mm long; spike 30- to 60-flowered	(16)

16 (15)	Bracts 22–28 mm long, dark brown with venation not evident; leaves mostly 15–30 mm wide	Watsonia pulchra
+	Bracts 16–40 mm long, pale brown with dark margins and paler veins; leaves mostly 10–15 mm wide	Watsonia densiflora

17 (12)	Flowers bright orange; upper part of perianth tube sub-cylindric, ± as long as lower part	Watsonia bachmannii
+	Flowers pink to purple; upper part of perianth tube funnel-shaped	(18)

18 (17)	Anthers 5–6 mm long; leaves linear, 3–6 mm wide	(19)
+	Anthers 6–9 mm long; leaves linear to lanceolate, 2–40 mm wide	(20)

19 (18)	Bracts herbaceous with brown papery margins, becoming dry and brown apically, (15–)20–25 mm long, not clasping rachis below; filaments exserted 3 mm from perianth tube	Watsonia palustris
+	Bracts dry and brown, (10–)12–16 mm long, clasping rachis below; filaments included in tube	Watsonia bella

20 (18)	Basal leaves linear, 2–3 mm wide, at least as long as spike (sometimes dry and broken); bracts dry and brown; tepals 14–16 mm long	Watsonia mtamvunae
+	Basal leaves linear to lanceolate, 4–40 mm wide; bracts herbaceous or dry and brown; tepals 16–28 mm long	(21)

21 (20)	Spike 3- to 8-flowered; anthers ± 9 mm long	(22)
+	Spike 10 to 25-flowered; anthers 6–9 mm long	(23)

22 (21)	Stem inclined at ground level; tepals 24–28 mm long; plants of open, stony, well-drained slopes	Watsonia inclinata
+	Stem erect; tepals 20–22 mm long; plants of permanently wet vleis and marshes	Watsonia pondoensis

23 (21)	Tepals 20–25 mm long; stems always simple	Watsonia transvaalensis
+	Tepals 16–19 mm long; stems frequently branched, branches sometimes 1or 2-flowered, thus resembling stalked flowers	(24)

24 (23)	Leaves 14–40 mm wide; spike 25 to 35-flowered; plants from Mpumalanga	Watsonia strubeniae
+	Leaves 5–14 mm wide; spike 10 to 20-flowered; plants from Eastern Cape	Watsonia amatolae

25 (1)	Flowers actinomorphic, rotate; upper part of perianth tube less than half as long as tepals; stamens central	Watsonia marginata
+	Flowers zygomorphic; upper part of perianth tube half or more as long as tepals; stamens unilateral, rarely pseudosymmetrical but then median stamen curved upward between laterals	(26)

26 (25)	Upper part of perianth tube above stamen insertion flared evenly from base to apex, usually ± twice as wide at mouth as near centre; tepals usually 1.5–2.0 times as long as upper part of tube; filaments included or shortly exserted up to 5 mm from tube; flowers usually pink to purple, rarely red, white or yellow	(27)
+	Upper part of perianth tube above stamen insertion ± cylindric, barely wider at mouth than near middle of upper part; tepals usually shorter than to ± as long as upper part of tube; filaments usually well exserted, 7–15 mm from tube, rarely less; flowers usually red to orange, or pink to purple	(37)

27 (26)	Stamens declinate	(28)
+	Stamens arcuate to horizontal	(33)

28 (27)	Floral bracts (15–)20–50(–70) mm long; perianth tube 25–50 mm long	(29)
+	Floral bracts 6–20 mm long; perianth tube 15–20 mm long	(30)

29 (28)	Bracts (15–)20–25(–33) mm long; upper part of perianth tube 8–14 mm long; filaments 13–15 mm long, well exserted from tube	Watsonia strictiflora
+	Bracts (25–)30–50(–70) mm long; upper part of perianth tube 5–8 mm long; filaments usually 6–12 mm long, shortly exserted from tube	Watsonia dubia

30 (28)	Anthers 4–8 mm long; plants small, rarely taller than 500 mm	(31)
+	Anthers 9–13 mm long; plants taller, usually more than 500 mm tall	(32)

31 (30)	Bracts broad-based and clasping stem; anthers 4–5 mm long, yellow (rarely purple)	Watsonia laccata
+	Bracts narrow throughout, not clasping stem; anthers 7–8 mm long, dark purple	Watsonia amabilis

32 (30)	Plants usually more than 1 000 mm tall; leaves glossy apple-green, rarely less than 20 mm wide; tepals (26–)30–36 mm long	Watsonia borbonica
+	Plants usually up to 500 mm tall; leaves dull green, 5–10 mm wide; tepals 22–30(–35) mm long	Watsonia rogersii

33 (27)	Spikes with at least 2 branches, each with at least 5 flowers; seeds 2-winged	(34)
+	Spikes unbranched or with short branches rarely with more than 2 flowers each	(35)

34 (33)	Upper part of perianth tube 8–12 mm long; bracts 10–18 mm long	Watsonia borbonica
+	Upper part of perianth tube 20–30 mm long; bracts 15–26 mm long	Watsonia versfeldii

35 (33)	Filaments ± twice as long as upper part of perianth tube, exserted 6–10 mm beyond tube; bracts 5–10 mm long	Watsonia galpinii
+	Filaments ± as long as upper part of perianth tube, included or shortly exserted up to 3 mm; bracts 9–30 mm long	(36)

36 (35)	Plants 150–350 mm high, unbranched; upper part of perianth tube 9–12 mm long; anthers 5–6 mm long; plants from Hottentots Holland Mtns	Watsonia distans
+	Plants 400–600 mm high, often branched; upper part of perianth tube 6–8 mm long; anthers 8–9 mm long; plants from Langeberg and Swartberg	Watsonia emiliae

37 (26)	Tepals up to half as long as upper part of perianth tube, ± 10 mm long	Watsonia aletroides
+	Tepals more than half as long as upper part of perianth tube	(38)

38 (37)	Floral bracts shorter, 5–14(–16) mm long (disregard lower 1 to 3 flowers)	(39)
+	Floral bracts longer, 15–45 mm long:	(49)

39 (38)	Filaments 10–20 mm long, included in perianth tube or exserted up to 5 mm	(40)
+	Filaments 25–45 mm long, well-exserted from perianth tube	(42)

40 (39)	Flowers pink	Watsonia paucifolia
+	Flowers orange to scarlet	(41)

41 (40)	Filaments exserted up to 5 mm from tube, 15–16 mm long; upper part of perianth tube 9–10 mm long, style dividing beyond anthers and well exserted	Watsonia minima
+	Filaments included in perianth tube, ± 10 mm long; upper part of perianth tube 10–15 mm long, style dividing below anthers with branches included in perianth tube	Watsonia elsiae

42 (39)	Tepals 12–16 mm long	(43)
+	Tepals 18–33 mm long	(44)

43 (42)	Floral bracts 5–8 mm long, usually shorter than spike internodes; leaf margins hardly thickened; plants from western mountains	Watsonia stokoei
+	Floral bracts 9–12 mm long, usually ± as long as spike internodes; leaf margins heavily thickened; plants from the Swartberg	Watsonia marlothii

44 (42)	Cauline bract-leaves much inflated; plants from the Cape Peninsula	Watsonia tabularis
+	Cauline bract-leaves not inflated; plants from Cape Peninsula and elsewhere	(45)

45 (44)	Floral bracts 7–10 mm long; capsules globose to ovoid; plants from Swartberg and east of George	Watsonia wilmaniae
+	Floral bracts 9–14 mm long but if only 9–10 mm long then capsules elongate-fusiform; capsules ovoid to fusiform	(46)

46 (45)	Inner bracts forked for 2–4 mm	(47)
+	Inner bracts entire or shortly forked up to 1.5 mm	(48)

47 (46)	Tepals 20–22 mm long; anthers ± 7 mm long; plants of marshes and seeps	Watsonia zeyheri
+	Tepals 24–33 mm long; anthers 9–12 mm long; plants of open slopes	Watsonia fourcadei

48 (46)	Filaments 16–28 mm long; flowers pink to purple or rarely red; tepals 8–15 mm wide; capsules narrowly obovoid	Watsonia knysnana
+	Filaments 30–38 mm long; flowers scarlet to dark red; tepals 4–10 mm wide; capsules elongate-fusiform	Watsonia angusta

49 (38)	Inner bracts forked for 2–4 mm	(50)
+	Inner bracts entire or shortly forked up to 1.5 mm	(52)

50 (49)	Foliage leaves dry at flowering; plants from Saldanha Bay, flowering April to July	Watsonia hysterantha
+	Foliage leaves green at flowering; plants not from Saldanha Bay, flowering September to January	(51)

51 (50)	Tepals 20–22 mm long; anthers ± 7 mm long; plants of marshes and seeps	Watsonia zeyheri
+	Tepals 24–33 mm long; anthers 9–12 mm long; plants of open slopes	Watsonia fourcadei

52 (49)	Outer floral bracts consistently longer than inner (disregard upper flowers)	(53)
+	Outer floral bracts ± as long as or shorter than inner	(56)

53 (52)	Inner (broader) tepals 4.5–9.0 mm wide and more than twice as long as wide; flowers pink; plants from Namaqualand	Watsonia rourkei
+	Inner (broader) tepals at least 10 mm wide and at least half as wide as long; flowers pink to purple or orange; plants from Cape Floristic Region	(54)

54 (53)	Flowers pink to purple; filaments 16–25(–30) mm long	Watsonia knysnana
+	Flowers orange to red; filaments (25–)30–45 mm long	(55)

55 (54)	Leaves (7–)12–18 mm wide, margins lightly to moderately thickened; plants from the Langeberg eastward	Watsonia pillansii
+	Leaves 6–15 mm wide, margins heavily thickened; plants from west of the Langeberg	Watsonia schlechteri

56 (52)	Leaves 50–85 mm wide, with pale, heavily thickened margins	Watsonia vanderspuyiae
+	Leaves 2–40(–50) mm wide	(57)

57 (56)	Tepals (28–)30–35 mm long; anthers 10–12 mm long	(58)
+	Tepals 15–26(–30) mm long; anthers 6–12 mm long	(59)

58 (57)	Flowers red: bracts 28–40 mm long	Watsonia spectabilis
+	Flowers pink; bracts 15–24 mm long	Watsonia versfeldii

59 (57)	Flowering stem branched and more than 400 mm high	Watsonia meriana
+	Flowering stem usually simple and up to 400 mm high	(60)

60 (59)	Upper perianth tube 13–16 mm long; bracts 15–22 mm long	Watsonia stenosiphon
+	Upper perianth tube 18–25 mm long; bracts 20–30 mm long	(61)

61 (60)	Bracts clasping stem only at base, usually flushed red; plants from loamy and sandstone soils	Watsonia coccinea
+	Bracts clasping stem in lower half, green; plants from limestone	Watsonia fergusoniae