Pultenaea mutabilis M.A.M.Renner & P . H .Weston var. mutabilis

Renner, Matthew A. M., Barrett, Russell L., Clarke, Steve, Clugston, James A. R. & Wilson, Peter H. Weston Trevor C., 2022, Morphological and molecular evidence refute a broad circumscription for Pultenaea glabra (Fabaceae: Mirbelieae), with implications for taxonomy, biogeography, and conservation, Australian Systematic Botany 35 (3), pp. 225-277 : 253-257

4a. Pultenaea mutabilis M.A.M.Renner & P. H.Weston var. mutabilis

Pultenaea sp.Lees Pinch ( L. A. S.Johnson s.n.: NSW17642) NSW Herbarium, PlantNet [https://plantnet.rbgsyd.nsw.gov.au/ accessed 22 Feb. 2022] .

Diagnosis

Pultenaea mutabilis var. mutabilis differs from P. mutabilis var. angusta in its oblanceolate leaves that are 1.3–3.1 (average 2.0) mm wide.

Woody shrub up to 4 m tall, erect with spreading branches, branching weakly whorled, with clusters of branches separated by long unbranched lengths of stem; branchlets densely leafy, green, with antrorse, loosely appressed hairs, then yellow–green. Stipules red–brown changing to brown or black with age; divided to near the base, lobes triangular, diverging, tapering but not long–acuminate; arched; keeled medially, keel faint, eccentric; margins irregular, bearing occasional hairs. Leaves oblanceolate, 9.8–21.7 (average 15.2) mm long, 1.3–3.1 (average 2.0) mm wide, not inrolled, nearly flat; adaxial surface with faint glaucous bloom; sparsely hairy on both ad- and abaxial surfaces; hairs short, antrorse, appressed; petiole hairy, the hairs short and antrorse; leaf cell surfaces smooth on both ad- and abaxial surfaces, adaxial surface hydrophobic; apex with a short apiculus. Leaf anatomy with three vascular traces present, median largest, no enlarged cells below the median vascular trace, ventral epidermis hyaline, no coloured cells except on the margin towards the apex. Inflorescence on leafy shoots that continue vegetative growth, no internode contraction; shoot continuing vegetative growth after flower production; stipules associated with subfloral leaves shorter and wider than those subtending vegetative leaves. Flowers pedicellate, pedicel hairy, hairs short and curled; a cluster of orange–red brown glandular trichomes present in the leaf axil at the base and either side of the pedicel; stipules associated with flowers larger than those on vegetative leaves, broader at base, not so deeply divided, disc quadrate, lobes triangular, not tapering to a narrow filament. Calyx tube yellow–green, lobes applegreen with red–brown margins, apices with or without a differentiated apiculus, often the three ventral lobes have an apiculus, whereas the upper two do not, but this is variable within and among specimens; lobes and tube sparsely hairy with short antrorse hairs; lobe margins densely hairy, hairs short and sometimes curved; lobes with vinous border, medially green. Bracteoles red–brown, narrow linear–lanceolate, exceeding the adjacent sinus or not, hairy on margin and lamina, medial hairs longer and straighter than marginal hairs that are short and curled; lamina base orange and membranous, otherwise green and coriaceous, often suffused with rose-red. Corolla yellow–orange, with a faint red semicircle at base of standard; keel yellow–orange, paler than standard; standard broadly transverse elliptic above a basal stipe; wings laterally splayed; asymmetrically narrow obovate above a narrow basal stipe, upper margin linear, apex broadly rounded, auricle broad and rounded or truncate; keel asymmetrically elliptic, upper margin linear, lower margin continuously curved, deepest at mid-point, apex broadly rounded, basal auricle triangular, acute. Ovary glabrous, style with short antrorse hairs on ventral surface immediately above ovary. Pods around 5 mm long in Blue Mountains plants, glabrous ( Fig. 18–20 ).

Distribution and ecology

Pultenaea mutabilis var. mutabilis is known from higher elevations of the Blue Mountains from Bilpin on the northern side of the Grose River in the south, at Gospers Mountain, at Lees Pinch in Goulburn River National Park, and around Denman, on the southern side of the Hunter Valley in the north. An outlying northern population occurs around Macintyre Falls in the Kwiambal National Park on the north-western slopes. Between Bilpin and Mount Tomah, and including Mount Irvine and Mount Wilson, P. mutabilis var. mutabilis occurs over shale bedrock, on faces and slopes, and broad ridges in wet sclerophyll forest dominated by a range of Eucalyptus species including E. piperita , E. cypellocarpa , and E. radiata . Pultenaea mutabilis var. mutabilis is a common component of the tall shrub layer within wet sclerophyll forests on and around the basalt caps of Mount Tomah, and Mount Irvine, and on the shaley soils surrounding Bilpin. Pultenaea mutabilis var. mutabilis generally grows at higher elevation than P. flexilis , which it replaces as elevation increases from east to west up the Blue Mountains, with overlap around Bilpin where the two species co-occur. At Lees Pinch in the Goulburn River National Park, P. mutabilis var. mutabilis grows over sandstone, within sandstone exposures and on talus slopes surrounding a sandstone outcrop. At Macintyre Falls, P. mutabilis var. mutabilis occurs over granite bedrock, in short dry-sclerophyll forest dominated by Eucalyptus caleyi and Callitris endlicheri with a dense shrub layer. The widely scattered known occurrences, and the variety of bedrock types over which the species may occur, suggest that P. mutabilis var. mutabilis may be widely distributed between its current known northern and southern limits.

All P. mutabilis var. mutabilis plants at Mount Irvine were burnt and killed by the Gospers Mountain Fire over the summer of 2019–2020, with no resprouting evident. However, during the summer and autumn of 2021, numerous seedlings were present, some up to 60 cm tall, suggesting mass recruitment from a pre-existing soil seed bank. At this time, the entire population comprised unflowered juveniles, and whatever ungerminated seed remained in the soil seed bank.

Recognition

Pultenaea mutabilis var. mutabilis can be recognised by the combination of branching architecture, leaf shape and ornamentation, and characters of the stipules and calyx. The branching architecture is irregular, wherein inflorescences are produced on shoots that continue vegetative growth and so do not affect architecture. The flowers are produced in the axils of leaves that are identical to those on vegetative shoot sectors, and the internodes separating sequential flowers are the same length as those separating sterile leaves. The stipules in both flowering and sterile shoot sectors are quite short and narrow, with narrow, straight lobes. The branchlets bear short antrorse hairs. The leaves are quite broad and oblanceolate (1.3–3.0 mm wide) and bear antrorse hairs on the abaxial surface, the cells of which are bulging, not mamillose, and bear fine granular ornamentation. The bracteoles are papery, and usually brown or reddish-brown. This combination of characters should prevent confusion with other members of the P. glabra complex, and most other Pultenaea species. Pultenaea mutabilis var. mutabilis has been confused with P. flexilis , but differs by its oblanceolate, rather than broadly oblong leaves, whose midvein on the abaxial surface is not prominent and covered by two or three rows of enlarged hyaline cells. Further, the leaf apex of P. mutabilis var. mutabilis is acute, whereas the apex of P. flexilis is broader, and tends to be mucronate. Pultenaea mutabilis var. mutabilis can be immediately distinguished from P. flexilis because the midrib on the underside of the leaf is narrow, and not covered by multiple rows of inflated epidermal cells. In Pultenaea flexilis , the midrib occupies approximately one-eighth of the leaf width, is prominent, raised, and pale, often a straw colour. By contrast, the midrib in P. mutabilis var. mutabilis occupies less than one 16th of the leaf width, is not, or hardly, raised, and is weakly differentiated in colour from the leaf. Pultenaea mutabilis var. mutabilis and P. flexilis also differ in leaf shape; the leaves of P. mutabilis var. mutabilis are narrow obovate, and taper evenly from the base to the broadest point, whereas the leaves of P. flexilis are nearly oblong in shape and widen abruptly from the base, such that there is usually an angle in the leaf outline immediately above the petiole, where the margin turns from this widening base into the long margin that extends towards the apex.

Pultenaea mutabilis var. mutabilis is similar to P. mutabilis var. angusta in almost all characters but differs by its consistently wider, oblanceolate leaves. The difference in leaf width is sufficient to impart completely different field aspects to these two taxa.

Pultenaea mutabilis var. mutabilis could be confused with P. forsythiana Blakely , but P. forsythiana has a long pungent acuminus at the leaf apex, a leaf that widens abruptly above the petiole, as in P. flexilis , and the stems are clothed in numerous, densely packed, orange–red erect and curled hairs. By contrast, P. mutabilis var. mutabilis has a short acuminus, a leaf that tapers gradually from the base, and stems clothed with sparse, hyaline, antrorse and appressed hairs.

Variation

Pultenaea mutabilis var. mutabilis expresses variation in several characters, including the relative lengths of calyx lobes, the length of the bracteoles relative to the calyx, and the hairiness of leaves. Plants from the eastern-fall catchments of the Blue Mountains have thinner leaves that are longer for their length than in plants from western fall catchments on the western side of the Great Dividing Range. Coriaceous-leaved plants also occur at Gospers Mountain, and similar plants occur on the north-western slopes around Macintyre Falls near Wallangra. The Macintyre Falls plants have oblong pods 9–10 mm long ( NSW 225730), which are twice as long as those observed on the thin-leaved forms from the Blue Mountains. Although the Macintyre Falls plants are most similar to P. mutabilis , and are certainly not P. flexilis , we note that their status, and the relationships between the thin-leaved and coriaceous-leaved forms from the Greater Blue Mountains Region require further investigation. It is entirely possible that, as circumscribed here, P. mutabilis var. mutabilis comprises a complex of three entities, each warranting some form of formal recognition.

Conservation status

Pultenaea mutabilis var. mutabilis is widely distributed, and locally common at some sites. The distribution of this taxon needs to be fully established before an informed assessment of threat can be made.+

Specimens examined

NEW SOUTH WALES: North Western Slopes , Macintyre Falls Fauna and Flora Reserve, ~ 22 km NNW of Ashford, 5 Oct. 1990, R. G. Coveny 14432 & R. O . Makinson, ( NSW 244919 ); Macintyre Falls , 3 km S of junction of Macintyre and Severn Rivers, near Wallangra , A. N. Rodd 4094, ( NSW 225730 ). Central Coast: Goulburn River National Park, Lees Pinch, off Wollara Road ; track to Lookout then S around base of outcrop, 16 Oct. 2018, M. A. M. Renner 9050 ( NSW 1052693 ); 16 Oct. 2018, M. A. M. Renner 9051 ( NSW 1052692 ); 16 Oct. 2018, M. A. M. Renner 9052 ( NSW 1052691 ); 16 Oct. 2018, M. A. M. Renner 9053 ( NSW 1052689 ); 16 Oct. 2018, M. A. M. Renner 9054 ( NSW 1052690 ); 16 Oct. 2018, M. A. M. Renner 9055 ( NSW 1052688 ). Central Tablelands, Cyrils Rock , 11 miles [~ 17.7 km] N of Gospers Mountain Army Airstrip , 9 miles [~ 14.4 km] NE of Glen Davis, on military road, 26 Apr. 1965, D. J. McGillivray 1150 & A. N . Rodd ( NSW 77998 ); Mt Tomah , 17 Feb. 1974, A. N. Rodd 2604 ( NSW 474237 ); Mt Tomah , Nov. 1898, J. H. Maiden ( NSW 37524 ); Mt Wilson , Oct. 1899, J. H. Maiden ( NSW 37523 ); Bowen Creek , SE of Mount Wilson, 9 Oct. 1966, R. G. Coveny s.n. ( NSW 474246 ); Bowen’s Creek, Bilpin–Mt Irvine road, 6 Oct. 1950, E. F. Constable, ( NSW 16348 ); Mount Irvine , 8 Oct. 1953, M. Bowyer ( NSW 37519 ); Mount Irvine , Oct. 1924, M. B. Welch ( NSW 474243 ); Mt Irvine, cemetery on Danes Way , 1 Oct. 2019, M. A. M. Renner 9154 & L. J . Gray ( NSW 1058848 ); 1 Oct. 2019, M. A. M. Renner 9155 & L. J . Gray 9155 ( NSW 1058852 ); Mt Irvine , 1 Oct. 2019, M. A. M. Renner 9156 & L. J . Gray ( NSW 1058853 ); 1 Oct. 2019, M. A. M. Renner 9157 & L. J . Gray ( NSW 1058855 ); 1 Oct. 2019, M. A. M. Renner 9158 & L. J . Gray ( NSW 1058856 ); 1 Oct. 2019, M. A. M. Renner 9159 & L. J . Gray ( NSW 1058857 ). Central Western Slopes: Denman , Oct. 1908, W. Heron ( NSW 37525 ); Wingen Maid Nature Reserve , 10 Nov. 1996, J. R. Hosking 1342, ( NSW 413425 ) .

Figures

Fig. 18. Pultenaea mutabilis var. mutabilis (= P. sp. Lees Pinch (L. A. S. Johnson s.n.: NSW 17642)) line drawing. (a) Habit, (b) flowering branch detail, (c) calyx side view, showing stamens, (d) standard petal, (e) wing, (f) keel, (g) flower, side view, (h) magnified calyx, side view, (i) leaf, adaxial surface, (j) leaf, abaxial surface, (k) leaf-surface detail showing hairs, adaxial, (l) leaf-surface detail showing hairs, abaxial, (m) stem detail showing stipule. Scale bar: 26.7 mm (a); 10 mm (b); 8 mm (c–g); 4 mm (h); 5 mm (i, j); 1.6 mm (k, l); 2.7 mm (m). All from NSW 1052688, a from dried material, b–m from spirit.

Fig. 19. Pultenaea mutabilis var. mutabilis (= P. sp. Lees Pinch (L. A. S. Johnson s.n.: NSW 17642)) photos from Lees Pinch. (a, b) Two views of a typical shoot, showing the flowers scattered among leaves. (c) Close up of flowering shoot, showing the nearly orbicular standard, the reddish keel, and the calyx, which appears glabrous but in fact bears short antrorse hairs. (d) Dorsal view of flowering shoot; note the glaucous bloom on adaxial leaf surface. (e) Ventral view of flowering shoot; note the glossy, green and thick-textured abaxial leaf surface. (f) Close-up of flower from front, showing prominent nectar guides, reddish keel and orbicular standard. (g, h) Close-up of flowering shoot sector, showing narrow stipules subtending leaves beneath flowers, and the papery bracteole on the calyx. All from plants at Lees Pinch, growing in the vicinity of voucher NSW 1052693.

Fig. 20. Pultenaea mutabilis var. mutabilis (= P. sp. Lees Pinch (L. A. S. Johnson s.n.: NSW 17642)) photos. (a) A typical shoot, showing the flowers scattered among the leaves. (b–e) Close-ups of flowering shoot sectors, showing flowers produced in association with normal vegetative leaves, the green upper and lower leaf surfaces, the calyces that appear glabrous, but which bear short antrorse hairs, and the pale yellow keel. Note the short sparse hairs on the branchlets in e. All from plants at Mount Irvine, growing in the vicinity of NSW1058848.