Plantago pyrophila Villarroel & J.R.I.Wood

Villarroel Segarra, D. & Wood, J.R.I. Kew Bull (2011) 66: 471. https://doi.org/10.1007/s12225-011-9298-4

Morphology General Habit

Densely tufted acaulescent perennial herb, the base 2 – 6 cm wide, 3 – 5 cm long, composed of dead compacted leaf petioles, the new leaves and inflorescence arising from the centre of the rosette

Morphology Roots

Roots to 14 cm long, formed of several subcylindrical tubers 1.5 – 4 cm wide, somewhat abruptly narrowed to a thread-like apex 1 – 4 cm long

Morphology Leaves

Rosettes with 3 – 10 living leaves; wool from leaf axils visible in the rosettes, reddish-brown, the hairs multicellular, up to 15 mm long, Leaves erect or ascending, 7 – 14 × 1.5 – 4 cm, oblong to oblong-elliptic when mature, apex acute, the base attenuate into the petiole which is widened and sheathing in the basal 1 – 2 cm, margin entire when young but developing scattered, obscure teeth when mature, veins 5, parallel, more prominent abaxially, young leaves densely pilose with spreading, flexuose hairs, glabrescent and usually completely glabrous when mature

Morphology Reproductive morphology Inflorescences Scape

Scapes 13 – 24 cm long, much exceeding leaves, whitish-pilose when young, glabrescent at maturity, flowers arranged in irregular groups in the apical half of the scape, appearing subverticillate, the groups mostly 4 – 8 mm distant; bracts 2 – 2.5 × 1.5 – 2 mm, ovate, glabrous except for a few apical cilia, 1-nerved, the apex acute to acuminate; sepals all similar in form, 2.5 – 3.2 × 1.5 – 2 mm, elliptic, apex obtuse or acute, glabrous except for a few apical cilia, corolla pale brown, glabrous, 4-lobed, the lobes all similar, 1.7 – 2 × 0.8 – 1.1 mm, 1-nerved, broadly lanceolate, apex acuminate, base abruptly narrowed, ± truncate; anthers 1.5 – 2 × 1 – 1.3 mm, exserted; ovary with 3 ovules and one seed developing, style 6 – 9 mm long, densely glandular pilose and probably sticky

Morphology Reproductive morphology Fruits

Capsule elliptic, 1-seeded, seeds 3 – 3.5 × 1.8 – 2 mm.

Distribution

Bolivia. Restricted to the serranías in the Municipio de Roboré in Chiquitos Province of Santa Cruz Department.

Ecology

This species grows on well-drained sandy soil in open, seasonally burnt grassland (campo limpo) on the flat-topped hills or mesetas of the SerraniasChiquitanas over a distance of some 25 km from Santa Bárbara in the west to Santiago de Chiquitos in the east, where it grows between 700 – 1000 m altitude. Precipitation in the zone is c. 1000 – 1150 mm per year but moisture may be increased by seasonal low cloud and mist. Plantago pyrophila grows in open grassland appearing soon after burning. It is almost certainly endemic to this mountain range and to Bolivia as no similar habitats are known within several hundred kilometres.

Conservation

Although very restricted in distribution and only known from three collections, this species is probably not especially vulnerable as there is no obvious threat to its habitat and suitable sites are numerous on the mesetas in the area. However, it probably merits careful monitoring as suggested in another recent paper on an endemic species of this region (Huaylla et al. 2010).

Phenology

This plant appears after burning, most commonly in October, and flowering is probably stimulated by fire. Fruiting material has been found in November but the plant has not been observed later in the growing season nor in areas which have not been burnt although the area has been visited regularly. Its appearance is thus very ephemeral as with several other perennial species with which it is often found, such as Pfaffiajubata Mart. and Vernonia desertorum Mart. ex DC.

Note

This species bears a superficial resemblance to many common species of Plantago such as P. media L. or P. australis Lam. However its tufted habit, tuberous roots and reddish “wool” in the leaf axils immediately set it apart from any species known to us. The corollas are all of one type with broadly lanceolate lobes, truncate at the base. The capsules seem always to be 1-seeded as only one ovule develops fully. We are unable to place this species with confidence in the infrageneric classification proposed by Rahn (1978) but it appears to belong to series Brasiliensis because of the structure of its bracts, corolla and anthers.

Plantago pyrophila is remarkable in several ways. It appears to be the only species of Plantago known from the cerrado biome. Mendonça et al. (2008) do not list any Plantago in their checklist of the cerrados. There are no records of Plantago species even as weeds in Mato Grosso (Dubs 1998) and we know of no other record of any Plantago from eastern Bolivia. All other populations of Plantago in South America are Andean or from temperate regions further to the south in Paraguay or Rio Grande do Sul in Brazil. Additionally it is a near perfect exemplar of adaptation to the cerrado habitat and survival through both periodic drought and burning. It is a pyrophyte and flowering appears to take place only after burning. The dense tufts formed by the dead leaf bases serve as protection against burning for the central living part of the plant and have a similar function to the leaf bases in Bulbostylisparadoxa C. B. Clarke and numerous grasses including Eriochrysisholcoides (Nees) Kuhlm. and Axonopusbrasilensis (Spreng.) Kuhlm. The tuberous roots are also paralelled in other typical cerrado species including Viguierasqualida S. Moore and two new species, one in Hyptis and the other in Vernonia found by the Darwin project in the same area and currently being described for publication.