Jacquemontia robertsoniana Buril & Sim.-Bianch.

Buril, M.T., Simão-Bianchini, R. & Alves, M. Kew Bull (2012) 67: 455. https://doi.org/10.1007/s12225-012-9361-9

Morphology General Habit

Shrub, erect, few branched, stems tomentose, greyish to ochraceous; tomentum formed by stellate trichomes, 3-rayed, the rays usually equal, c. 0.1 mm, pedunculate

Morphology Stem

Internodes 0.2 – 0.6 cm long, sometimes shorter

Morphology Leaves

Leaf blade 1 – 1.6 × 0.9 – 1.3 cm, papery, entire, oval to orbicular or rarely elliptic, oblong, ovate or obovate, base rounded, apex apiculate to acuminate and on the leaves of the terminal branches becoming longer, caudate to obtuse with an acumen, tomentose, greyish; veins not evident

Morphology Leaves Petiole

Petiole 0.05 – 0.1 cm long

Morphology Reproductive morphology Inflorescences

Inflorescence terminal, compound cymes, capituliform, c. 6-flowered, sessile, terminal; modified bracteoles lacking

Morphology Reproductive morphology Flowers Calyx

Sepals unequal, 3 outer 0.7 – 0.75 × 0.2 – 0.25 cm, chartaceous, entire, lanceolate to ovate, base rounded, apex long acuminate, 2 lanulose inner 0.55 – 0.6 × 0.1 – 0.15 cm, entire, lanceolate, base rounded, apex acute, puberulent in the central region, with margins membranous

Morphology Reproductive morphology Flowers Corolla

Corolla c. 1.2 cm long, funnelform, weakly lobed between episepalic veins, with sparse trichomes on midpetaline band on abaxial face, blue

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens heterandrous, 2 longer c. 0.6 cm long, 3 smaller c. 0.4 cm long, filament glabrous, anthers elliptic, c. 1.5 mm long, base subcordate, apex rounded

Morphology Reproductive morphology Flowers Gynoecium Style

Style c. 0.5 cm long, stigmatic lobes elliptic, oval-flat; nectary absent; ovary c. 1 mm long, glabrous, 2-locular, 2 ovules per locule

Morphology Reproductive morphology Fruits

Fruits not seen

Distribution

Brazil: Bahia, Chapada Diamantina (Municipalities: Abaíra, Mucugê, and Palmeiras). Map 1.

Ecology

Jacquemontia robertsoniana occurs in open vegetation and rocky fields, in a semi-arid climate, c. 800 m alt.

Conservation

Jacquemontia robertsoniana should be classified as Vulnerable (VU) according to the IUCN red list (2001) B1 criteria, because the estimated extent of occurrence for this species is less than 20,000 km², it is restricted to less than ten locations, and a continuing decline in the number of mature individuals is inferred. Although this species occurs in a preserved area (Chapada Diamantina National Park), access is not closely monitored.

Note

Jacquemontia robertsoniana is also morphologically similar to J. hallierianaOoststr. and J. decipiensOoststr. (Table 1). The first species is distinguished by its ovate to orbicular leaves and apparent veins, sessile and capituliform inflorescences with many flowers, and two falcate bracteoles near each pedicel. J. decipiens has a lanate, silver indumentum. Jacquemontia is usually a vine; however, a small group of species is erect, with herbaceous to somewhat woody stems and, although these species are not taxonomically related, they share many similar characteristics. Among the shrubby species, J. robertsoniana could be related to J. ochraceaSim.-Bianch. & Pirani because of the branching arrangement, leaf shape and colour, indumentum, and inner sepal shape. However, on the terminal branches of J. robertsoniana, the leaf apex is caudate, while in J. ochracea the apex is always apiculate or retuse with a small arista. These species can also be distinguished by the usually longer (1.7 – 4.5 cm long) and frequently orbicular leaves of J. ochracea, and the axillary or terminal cymes, the presence of linear bracteoles, and by the 8-rayed trichomes in J. ochracea. In all samples analysed from both species, the branching of trichomes proved to be constant. Thus, it can be used to distinguish J. robertsoniana from J. ochracea; although this character is sometimes quite variable for other species in the genus. So far, both species are reported to occur in the complex of mountains of the Cadeia do Espinhaço, which holds a high number of endemic plants (Rapini et al. 2008). While J. robertsoniana is restricted to the central part of this range in the state of Bahia, J. ochracea is only known from its southern part in the state of Minas Gerais (Simão-Bianchini & Pirani 2005) (Map 1). The epithet honors Dr Kenneth Robertson, who contributed to the taxonomy of Jacquemontia .