Lebeckia Thunb. section Lebeckia

le Roux, M. M. & Van Wyk, B. - E., 2007, A revision of Lebeckia sect. Lebeckia: The L. sepiaria group, South African Journal of Botany 73 (1), pp. 118-130 : 121-122

3.2. The section Lebeckia

Lebeckia Thunb. section Lebeckia .

Type: L. sepiaria (L.) Thunb., chosen by Hutchinson in Gen. Flow. Pl.: 358 (1964).

Spartium L. , Pl. Rar. Afr.: 91 (1760), Sp. Pl.: 995 (1764), Gmelin, Syst. Nat. 2 (2): 1088 (1792), pro parte.

Lebeckia Thunb., Prod. Pl. Cap. : 122 (1800), Fl. Cap.: 561 (1823), pro parte majore; Eckl. and Zeyh., Enum.: 192 (1836), pro parte majore; E. Mey. in Linnaea 7: 155 (1832), Comm. Pl. Afr. Austr. 1: 34 (1836), pro parte majore.

Sarcophyllum E. Mey. in Linnaea 7: 155 (1832), Comm. Pl. Afr. Austr. 1: 34 (1836).

Eu-Lebeckia Benth. in Hook., Lond. J. Bot. 3: 358 (1844), synon. nov.

Phyllodiastrum Benth. in Hook., Lond. J. Bot. 3: 358 (1844), synon. nov.

Erect to prostrate, slightly to markedly glaucous suffrutices. Leaves simple, acicular, glabrous, sparse or dense, spirally arranged, often articulated near the middle, mucronulate. Inflorescences terminal, short or elongate, laxly to densely manyflowered; rachis usually furrowed; flowers small or large (6– 18 mm long), yellow; bracts ovate to lanceolate, acuminate, caducous; bracteoles narrowly triangular, acuminate. Calyx equally to subequally lobed, lobes deltoid, ± as long as the tube, tips minutely pubescent on the inside. Petals yellow, sometimes fading to orange or rarely purple ( L. longipes ), invariably totally glabrous. Standard lanceolate to orbicular; apex obtuse. Wings oblong; apex obtuse; sculpturing present or absent. Keel rostrate, pockets sometimes present. Stamens fused into an open sheath, upper third free; anthers 10, 5 oblong and basifixed, 5 short and dorsifixed (vexillary stamen only slightly shorter than long anthers). Pistil sessile to markedly stipitate; ovary oblong to linear; ovules ± 6–20; style shorter than the ovary, curved upwards. Pods linear or ovoid, straight or slightly deflexed, up to 12 mm wide. Seeds reniform.

3.2.1. Diagnostic characters

Species of Lebeckia section Lebeckia differ from all other species in the genus by their needle-like leaves, which are terete (never flat).

3.2.2. Distribution

Lebeckia section Lebeckia (and also the L. sepiaria group) are endemic to the Cape Floristic Region, from Namaqualand to Port Elizabeth.

Key to the species of Lebeckia section Lebeckia

1a. Keel spirally twisted:

2a. Fruit up to 50 mm long; short-lived fireweed; L. wrightii flowers 1–3 per inflorescence

2b. Fruit 60–120 mm long; perennial herb; L. pauciflora flowers more than 5 per inflorescence

1b. Keel not twisted:

3a. Calyx teeth longer than the tube L. grandiflora 3b. Calyx teeth shorter than the tube:

4a. Leaves articulated near the middle:

5a. Fruit long-stipitate (stipe 10–20 mm long); L. carnosa flowers very widely spaced on rachis

5b. Fruit sessile or short-stipitate (stipe less than

5 mm long), flowers usually densely spaced on rachis

(if somewhat widely spaced, then the fruit is flat):

6a. Fruit ovoid (up to 13 mm long) L. brevicarpa

6b. Fruit oblong to linear (more than 15 mm long):

(continued on next page)

7a. Fruit oblong (up to 6x longer than wide), flat, upper suture with distinct margin or wing:

8a. Flowers 6–11 mm long; L. meyeriana fruit 20–35 mm long

8b. Flowers ca. 15 mm long; L. macowanii fruit ± 50 mm long

7b. Fruit linear (more than 10× longer than wide), terete or semi-terete, upper suture without a margin or wing:

9a. Flowers usually up to 8 mm long; L. gracilis upper lateral sinuses of calyx± as wide as medial sinus and lower lateral sinuses; southern coastal distribution from Bredasdorp to Port Elizabeth

9b. Flowers more than 9 mm long; upper lateral sinuses of calyx much wider than medial sinus and lower lateral sinuses; western coastal distribution from Namaqualand and inland to the Cedarberg and eastwards to Heidelberg:

10a. Fruit dehiscent, not spongy, subterete, L. ambigua ± 2 mm wide, sometimes falcate

10b. Fruit indehiscent, spongy, terete, L. sepiaria more than 4 mm wide, straight, often somewhat torulose

4b. Leaves not articulated:

11a. Fruit long-stipitate (stipe 15 mm or longer) L. longipes

11b. Fruit sessile or short-stipitate L. plukenetiana (stipe up to 5 mm long)

Within the section Lebeckia , there are four species groups:

(1) the L. sepiaria group — four species with terete or semi-terete, ± sessile pods and a generally erect, virgate habit ( Fig. 1 ).

(2) the L. plukenetiana E. Mey. group — five species with stipitate, flat pods of up to 75 mm long.

(3) the L. wrightii (Harv.) Bolus group – one species – a short-lived fireweed with stipules and flat pods.

(4) the L. pauciflora group — two species with relatively long calyx lobes and linear, stipitate, semi-terete pods of more than 70 mm long.

Figures

Fig. 1. Growth form (habit) and fruit shape in the four species of the Lebeckia sepiaria group:(a) L.ambigua (Namaqualand form, photo taken at Klawer); (b) L. brevicarpa (Pakhuis Pass); (c) L. gracilis (Bredasdorp form, taken at Still Bay); (d) L. sepiaria (Clanwilliam form; photo taken at Elandskloof); (e) fruit and flowers of L. ambigua (Clanwilliam); (f) fruit of L. brevicarpa (Pakhuis Pass); (g) fruit of L. gracilis (Still Bay); (h) fruit of L. sepiaria (Clanwilliam form, photo taken at Citrusdal). All photos by B.-E. van Wyk.