Amphibolia L.Bolus ex Herre 1971: 70; L.Bolus JSAB 1965: 169 nomen invalid.; Toelken & Jessop 1976: 64; Hartmann & Dehn 1989: 179–182; Hartmann Bradleya 1996: 29–56; Hartmann Bradleya 1998: 44–51; Hartmann 2001: 37–39 Lectotypus A. maritima L.Bolus ex Toelken & Jessop = A. laevis (Aiton) H.E.K.Hartmann Etym Gk amphibolia, uncertainty or doubt, because the combination of closing bodies and broad valve wings occurring also in Stoeberia raised doubts about the placement of the type species.

Low shrubs to c. 40 cm tall, ∅ to 70 cm, or higher and not so broad, I white to yellowish or greyish; L club-shaped to trigonous, epidermis smooth, stomata hardly sunken, outer walls rather thin, with a thin layer of calcium oxalate sand, often grey from wax; Fl 1–3 per cyme, bracteate and bracteolate, petals pink with a complicated marking: the basal darker line lies in a lighter whitish or greenish rim separating the line from the outer dark purple area, in some species petals uniformly pink or white, filamentous staminodes often apically dark purple, surrounding the central stamens in a distinct, broken cone resembling a pitcher-shape in fresh flowers: the bases of the filaments almost horizontally arranged, the upper halves turning upwards rather abruptly near the middle, stigmas short, densely papillate outside as well (Fig. 2), nectary in a lophomorphic ring; Fr always persisting on the plant, base funnel-shaped, merging into the stalk, valve wings very broad and rectangular, covering membranes complete with a low distal recurving under which closing rodlets or closing ledges are placed, closing bodies small, 5, rarely 6 locules; S glabrous and almost round; Ecol in sand, gravel, or rocks, from below 100 to above 300 mm rainfall p.a. in winter, fog from the sea (Fig. 1); Distr Lüderitz-South, Namibia; districts along the W coast of S Africa.

Fig. 1
figure 1

Distribution of Amphibolia is restricted to coastal or coast-near habitats along the south-western coast of southern Africa, where saline spray and morning fog from the sea can be expected regularly (Copyright H.E.K. Hartmann)

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Note: Hartmann (1993: 63) placed Amphibolia as a synonym with Eberlanzia, a view not upheld here. The less xeromorphic leaves, the peculiar construction of the androecium and the stigmas being papillate on their outside, the very broad valve wings and the funnel shaped base of the fruit of Amphibolia permit at present a clear distinction and circumscription. Features shared with Eberlanzia are the whitish stems and the glabrous, almost round seeds. Amphibolia should be studied again in its relation to the genera Stoeberia (also with very broad valve wings) and Ruschianthemum, both with whitish stems as well. The complex of the four genera, until now included in the Ruschia-group (Hartmann 1991, 1993), may represent an evolutionary branch of its own. Amphibolia and the supposedly related species need a revision to clarify the taxonomy with confidence. Most species grow allopatrically, but A. rupis-arcuatae and A. succulenta are in some places found together.

Key to the Species of Amphibolia

1.

Capsules with 5 locules, 6 occurring only as an exception in few populations, base of fruit long, funnel-shaped

2

–

Capsules with 6 locules throughout, base of fruit short, funnel- or bell-shaped

A. obscura

2.

Leaves short (length at most double the breadth or width), trigonous, densely set, base of fruit mostly enclosed by bracteoles

A. rupis-arcuatae

–

Leaves more than twice, mostly 3–4 times as long as broad or thick, club-shaped, base of fruit raised well above the bracteoles

3

3.

Leaves slender, 15–30 mm long, 4–5 mm broad and thick

A. succulenta

–

Leaves thick, 10–20 mm long, 8–10 mm thick, often crescent-shaped in side view

4

4.

Capsule with a distinct closing rodlet at the distal end of the covering membrane, closing body hook-shaped

A. laevis

–

Capsule with a closing ledge at the distal end of the covering membrane, tiny closing body knob-shaped

A. saginata

  • A. gydouwensis ≡ Phiambolia incumbens

  • A. hallii ≡ Phiambolia hallii

  • A. hutchinsonii = A. laevis

A. laevis (Aiton) H.E.K.Hartmann ≡ Mesembryanthemum laeve Aiton 1789: 187 nec Thunberg 1791: 16 nomen illeg. NT, designated by Hartmann 2001: 38, drawing 191/142 M by Duncanson 31.6.1825 (K!) = Ruschia hutchinsonii L.Bolus NM2 1928: 23 ≡ M. hutchinsonii (L.Bolus) N.E.Br. GC 1930: 32 ≡ A. hutchinsonii (L.Bolus) H.E.K.Hartmann Bradleya 1998: 46 T Hutchinson 288 (BOL!) = A. maritima L.Bolus ex Toelken & Jessop 1976: 64; L.Bolus 1965: 169 nomen invalid. ≡ Ruschia maritima (L.Bolus ex Toelken & Jessop) G.D.Rowley NCSJ 1978: 62 T Hall 2885 (BOL!) = Ruschia promontorii L.Bolus NM2 1929: 121 ≡ M. pansifolium N.E.Br. GC 1930: 32 T Rohland 1543/20 (BOL!).

Low shrubs to 20, rarely to 40 cm h, ∅ to 70 cm, adventitious roots on decumbent branches, short side branches erect, I whitish to yellowish; L light green to yellowish grey, club-shaped, emarcescent old ones remaining on the stem for some time, 10–20 mm l, 6–8 mm b, 6–10 mm t; Fl petals pale pink (Fig. 2); Fr base long, funnel-shaped, closing rodlets prominent at the end of the covering membranes, closing body hook-shaped, 5 locules; S 0.9–1 mm l, c. 7.5 mm b; Ecol gravelly coastal plains, up to 350 mm rainfall p.a. in winter, fog; Distr from Vredendal to Simonstown, WC, S Africa.

Fig. 2
figure 2

Amphibolia laevis with an urceolate flower and the typical colouring (Copyright H.E.K. Hartmann)

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Note: Although it has been known since 200 years that the name M. laeve had been used for two different species, it was only a decade ago found that a drawing agreeing with the description of Aiton is kept at Kew. Based on the club-shaped leaves withering slowly, the figure is chosen as the neotype of the species which can, therefore, been placed in the genus Amphibolia. References to this species include: Gmelin 1791: 845; Haworth 1795: 254–255; Willdenow 1799: 1044; Haworth 1803: 64–65; Aiton 1811: 232–233; Haworth 1812: 302–303; Haworth 1821: 154–155. Of these authors, Willdenow indicated a purple flower, followed by Haworth 1795 and Aiton 1811. Ruschia promontorii is placed here in synonymy based on similarities in leaf surface only, because fruits are absent and the flowers are inadequately preserved. A. laevis is very similar to A. saginata and A. succulenta, all three perhaps subspecies of one species.

  • A. littlewoodii ≡ Lampranthus mutatus

  • A. maritima = A. laevis

A. obscura H.E.K.Hartmann Bradleya 1998: 47 T Hartmann et al. 20805 (HBG!).

Broad shrubs to 40 cm h, ∅ to 70 cm, I 35–40 mm l, ∅ to 5 mm; L bright light green, club-shaped to terete, 15–45 mm l, 5–10 mm b and t; Fl 1–3, ∅ 18 mm, bracteoles hooded, embracing the base of the flower, K 6, petals purplish-pink, 8 mm l, to 1.5 mm b, filamentous staminodes absent (?), anthers white; Fr base short, funnel-shaped, top raised, but rims low, covering membranes with thick and long closing ledges, closing body nearly hook-shaped, 6 locules; S 1.1 mm l, 0.8 mm b; Ecol on rocky slopes in shallow places, <100 mm rainfall p.a. in winter, fog (Fig. 3); Distr NW Namaqualand, NC, S Africa.

Fig. 3
figure 3

Amphibolia obscura, the big yellowish green plants on a gentle stony slope (Copyright H.E.K. Hartmann)

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Note: Based on capsule morphology and leaves, the species is placed in Amphibolia, albeit the flowers do not show an expressed pitcher-shape.

A. rupis-arcuatae (Dinter) H.E.K.Hartmann Bradleya 1996: 34 ≡ M. rupis-arcuatae Dinter FR 1923: 151 ≡ Ruschia rupis-arcuatae (Dinter) Friedrich 1960: 564 ≡ Stoeberia rupis-arcuatae (Dinter) Dinter & Schwantes ZSK 1927 in Schwantes ZSK 1927: 17 T Dinter 3880 (B) = Ruschia namaquana L.Bolus NM1 1928: 140 ≡ M. namaquanum (L.Bolus) N.E.Br. GC 1930: 32 NT, corrected by Hartmann 2001: 39, Pillans 5037 (not 5032, as in Hartmann Bradleya 1998: 47) (BOL!).

Erect shrubs, often funnel-shaped when young from diagonal branches (Fig. 4), later filling up by apical or mesotonic branching, to 50 cm h, ∅ to 50 cm; L placed densely on short shoots resulting in a rather compact appearance of the shrub, trigonous, 12–15 mm l, 5–8 mm b and t, epidermal cells a little raised, wax cover continuous and with a dense layer of vertically arranged platelets; Fl ∅ up to 12 mm, 25–32 petals in 5 groups, white, with a darker central stripe, rarely apically pale pink, 21–30 filamentous staminodes apically dark reddish purple, 53–65 white stamens; Fr base long, funnel- to bell-shaped, mostly enclosed by the bracteoles, covering membranes with a distal closing ledge at the end, closing body a small hook, 5 locules; S 0.85–1 mm l, 0.7–0.8 mm b; Ecol in sand or gravel near the sea, often near rocks, <100 mm rainfall p.a. in winter, fog; Distr Lüderitz-South, Namibia; NE Namaqualand, NC, S Africa.

Fig. 4
figure 4

Amphibolia rupis-arcuatae in sand with widely spreading young side branches which will later fill up to form dense bushes; note the fine sand in the front, later to be caught by the branches (Copyright H.E.K. Hartmann)

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Note: Dinter (1923) already noticed the peculiar features of the flower structure agreeing with that of A. laevis but the geographical distance probably hindered the recognition of the similarity of the flower morphology, which, until this date, also represents a rarity in Mesembryanthema. A. rupis-arcuatae is restricted to coastal or coast-near habitats and shows a distribution pattern similar to that of Eberlanzia sedoides. Since the species are also similar in leaf-shape, they have often been confused.

A. saginata (L.Bolus) H.E.K.Hartmann Bradleya 1998: 48 ≡ Ruschia saginata L.Bolus NM3 1937: 104 LT, designated by Hartmann 2001: 39, Holloway 6 II (chosen from two sheets, BOL!) = Ruschia stricta L.Bolus var. turgida L.Bolus NM2 1930: 207 T Frames 19209 (BOL!).

Low shrubs to 40 cm h, ∅ to 70 cm; L club-shaped to crescent-shaped, 10–20 mm l, c. 8 mm b and t; Fl petals 27–40, purple with a basal, dull, dark purple line separated by a whitish rim from the dark red outer area, 16–26 whitish filamentous staminodes, 62–86 purple stamens; Fr base long, funnel-shaped, closing ledges at the distal end of the covering membranes, closing body reduced to a tiny knob, 5 locules; S 1–1.2 mm l, 0.8–0.9 mm b; Ecol on rocky slopes in mountains, <100 mm rainfall p.a. in winter (Fig. 5); Distr Lüderitz-South, Namibia.

Fig. 5
figure 5

Amphibolia saginata as yellowish low shrubs amongst stones on a gentle slope, only little sand has been caught by the stones (Copyright H.E.K. Hartmann)

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Note: Up to now, the species has only been found in the mountains of the southern Namib, although the most similar A. laevis occurs almost 1000 km south near the Cape of Good Hope. Together with A. succulenta, settling between the two, the species should be studied in more detail.

  • A. stayneri ≡ Phiambolia littlewoodii

A. succulenta (L.Bolus) H.E.K.Hartmann Bradleya 1998: 48 ≡ Ruschia succulenta L.Bolus NM1 1928: 144 ≡ M. succulentum (L.Bolus) N.E.Br. GC 1930: 33 T Pillans 5791 (BOL!).

Low shrubs to 40 cm h, ∅ to 70 cm; L greyish-green, club-shaped, slender: 15–30 mm l, 4–5 mm b and t; Fl ∅ 14–17 mm, petals purple, the darker dull line at the base separated from the rest by a whitish rim, 28–33 petals, 17–32 filamentous staminodes, 55–87 stamens; Fr base long, funnel-shaped, covering membranes with closing ledges or broad rodlets at their distal ends, closing body a tiny hook, 5 locules; S 0.8–0.9 mm l, 0.7–0.8 mm b; Ecol in loamy places amongst rocks or gravel (Fig. 6), <100 mm rainfall p.a. in winter, fog; Distr NW Namaqualand, NC, S Africa.

Fig. 6
figure 6

Amphibolia succulenta: the greyish-green cushions settle preferably below slopes in more sandy ground (Copyright H.E.K. Hartmann)

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Note: Similar in flower and fruit construction to A. laevis and A. saginata. Characteristic of the species are the slender, club-shaped leaves.