Electronic Flora of South Australia Species Fact Sheet

Macrocystis pyrifera (Linnaeus) C. Agardh 1820: 47.

Phylum Phaeophyta – Order Laminariales – Family Lessoniaceae

Selected citations: Cribb 1954: 1, figs 1–4,7. Harvey 1862: pl. 202. Skottsberg 1907:80, pl. 9. Womersley 1954a: 118, pls 1,3,4; 1967: 248.

Thallus (Fig. 118A) medium to dark brown, usually 4–10 (–20) m high, bearing many fronds with broad blades from the holdfast. Holdfast (Fig. 118B) conical, 10–50 cm high and across, with one or a few central erect stipes bearing on all sides cylindrical, subdichotomous haptera 2–4 mm in diameter; epilithic. Stipe 3–6 times subdichotomous shortly above the holdfast, branches terete to compressed, 3–8(40) mm in diameter, 4–10 m long with the upper parts bearing blades unilaterally. Terminal blades (Fig. 118A) usually broadly falcate, with 8–20 young lateral blades in progressive stages of differentiation by splitting; terminal blade and attached segments L/B 1–5. Lateral blades broadly lanceolate to ligulate, basally constricted, 30–150 cm long and usually (3 -)5–15 cm broad, smooth to rugose with denticulate margins with slender teeth 2–6 (–9) mm long, basally stipitate with an elongate-ovoid to pyriform (or occasionally subspherical) pneumatocyst, usually 4–12 cm long and 1–4 cm in diameter. Structure of blades with a central filamentous medulla and cortex of isodiametric to elongate cells, with an outer meristoderm; stipes (Fig. 121D) with an outer medulla containing sieve-tube like elements running longitudinally amongst the hyphae, and with numerous, small, mucilage canals with secretory cells in the outer cortex.

Reproduction: Reproduction from rounded to irregular, dark brown, sori (Fig. 121E) on small basal blades attached to the lower stipes; unilocular sporangia clavate, 30–60 µm long and 6–10 µm in diameter, accompanied by longer clavate paraphyses 40–75 µm long and 6–10 µm in diameter, with a gelatinous covering to the sorus.

Type from "oceano Aethiopica" (southern Atlantic); in LINN, 1274.59? (see Womersley 1954a, p. 111).

Selected specimens: Port Elliot, S. Aust., drift (Womersley, 7.iii.1959; ADU, A22192). Bluestone Bay, Freycinet Pen., Tas., 10–12 m deep (Brown, McGeary & Womersley, 4.xi.1982; ADU, A56452). Port Arthur, Tas., sublittoral (Cribb, 29.iii.1950; ADU, A16378). Great Taylor Bay, Bruny I., Tas., 2–7 m deep (Shepherd, 7.ii.1970; ADU, A35551).

Distribution map based
on current data relating to
specimens held in the
State Herbarium of SA

Distribution: The subantarctic region; New Zealand; South America north to Callao, Peru, and to about 50°S on the east coast; Pacific North America from Magdalena Bay, Baja, California to the Monterey Peninsula, California.

In southern Australia, on the east and south-east coast of Tasmania, with drift specimens occasional on Victorian or South Australian coasts.

Taxonomic notes: Gametophytes 100–300 µm across, filamentous, the female with few branches and relatively broad cells, forming eggs in terminal cells, the male much branched, slenderer, with small, lateral antheridia.

M. pyrifera appears to be confined to south east Tasmania in southern Australia (see comments following M. integrifolia), occurring mainly in deeper water, where it is dominant in depths of 8–22 m (Edgar 1984, p. 179).

References:

AGARDH, C.A. (1820). Species Algarum. Vol. 1, Part 1, Fucoideae, pp. 1–168. (Lund.)

CRIBB, A.B. (1954). Macrocystis pyrifera (L.) Ag. in Tasmanian waters. Aust. J. mar. Freshw. Res. 5, 1–34, Plates 1–4.

EDGAR, G.J. (1984). General features of the ecology and biogeography of Tasmanian subtidal rocky shore communities. Pap. Proc. R. Soc. Tas. 118, 173–186.

HARVEY, W.H. (1862). Phycologia Australica. Vol. 4, Plates 181–240. (Reeve: London.)

SKOTTSBERG, C. (1907). Zur Kenntnis der Subantarktischen und Antarktischen Meeresalgen. I. Phaeophyceen. Wissenschaftliche ergebnisse der Schwedischen Südpolar-expedition 1901–1903, 4, 1–172, Plates 1–10.

WOMERSLEY, H.B.S. (1954a). The species of Macrocystis, with special reference to those on southern Australian coasts. Univ. Calif Publ. Bot. 27, 109–132.

WOMERSLEY, H.B.S. (1967). A critical survey of the marine algae of southern Australia. II. Phaeophyta. Aust. J. Bot. 15, 189–270.

The Marine Benthic Flora of Southern Australia Part II complete list of references.

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
Part II
©Board of the Botanic Gardens and State Herbarium, Government of South Australia

Illustrations in Womersley Part II, 1997: FIGS 118, 121D,E.

Figure 118   enlarge

Fig. 118. Macrocystis pyrifera (ADU, A56452). A. Falcate terminal blade and developing laterals. B. Holdfast in sectional view (after Womersley 1954a, pl. 4).

Figure 121   enlarge

Fig. 121. A–C. Lessonia corrugata (A, ADU, A54525; B,C, ADU, A35562). A. Transverse section of thallus with corrugations, cortex with mucilage cavities, and filamentous medulla. B. Transverse section of thallus showing position of a sporangial sorus. C. Detail of transverse section with unilocular sporangia and paraphyses, cortex, and filamentous medulla. D,E. Macrocystis pyrifera (ADU, A56452). D. Transverse section (diagrammatic) of stipe. E. Detail of transverse section of thallus with unilocular sporangia and paraphyses, cortex, and filamentous medulla. F–H. Macrocystis angustifolia ( F, ADU, A16088; G,H, ADU, A57134). F. Detail of transverse section of thallus with unilocular sporangia and paraphyses, cortex, and filamentous medulla. G,H. Gametophytes from culture, G female, H male. I–K. Ecklonia radiata (I, ADU, A57144; J,K, ADU, A57135). I. Detail of transverse section of thallus with unilocular sporangia and paraphyses, and cortex. J,K. Gametophytes from culture, J female, K male.

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