Juniperus navicularis (Portuguese prickly juniper, piorro) description

Juniperus navicularis

Gand. 1910

Common names

Portuguese prickly juniper, sea sands juniper; zimbro-galego, piorro [Portuguese].

Taxonomic notes

Type: Portugal, Ribatejo, Portela de Sacavem, Alcochete. A. X. Pereira Coutinho s.n. Holotype LISU.

Synonymy: Juniperus oxycedrus L. subsp. transtagna Franco 1963; Juniperus oxycedrus L. var. transtagna (Franco) Silba 1984.

Populations of J. navicularis were originally assigned to J. oxycedrus, and later, to var. (or subsp.) transtagna of that species, although as early as 1910 Gandoger recognized them as morphologically distinct and described J. navicularis. That assignment was not generally accepted, though, until molecular analyses showed that J. oxycedrus s.l. included several cryptospecies that belong in a separate clade of Section Juniperus: J. brevifolia of the Azores, J. navicularis of coastal Portugal, and J. deltoides from Italy to Israel and Iraq (Adams and Schwarzbach 2012, Adams 2014). This has correspondingly reduced the scope of J. oxycedrus to include only its type subspecies.

Description

Evergreen dioecious shrubs to 2 m tall, branching at the base, with a fastigiate crown of somewhat pendulous branches. Bark brown, exfoliating in thin plates. Leaves needle-like, 4-12 × 1-1.5 mm, obtuse, with with two adaxial glaucous stomatal bands. Pollen cones fertile in summer. Seed cones maturing in 2 years, globose to pyriform, yellow maturing red or coppery red, 7-10 mm diameter, with usually 3 seeds per cone (Adams 2014).

Distribution and Ecology

Portugal and Spain. In Portugal it is mainly found south of Lisbon, around the Sado Estuary and the Setubal Peninsula with a few other isolated localities such as Alentejo and Algrave. In Spain it is found in Huelva and near Cadiz. It occurs in Pinus pinaster forest on coastal sandy soils and stabilized dunes, at elevations to 220 m. Other associated species include Quercus lusitanica, Daphne gnidium, Arum neglectum and Chamaerops humilis, and many stands have been afforested with Eucalyptus and Pinus pinea (Adams 2014, Farjon 2013, Thomas 2019). An age structure found low regeneration rates and a predominance of stems 20-40 years old, with highest cone production recorded in older female plants. At most sites only one sex was recorded, suggesting that reproduction is primarily clonal (Carmona-Velasco et al. 2022).

The IUCN classifies this species (under the name J. oxycedrus subsp. transtagna) as "Near Threatened" due to habitat loss associated with urbanization. However, the species occurs widely in protected areas and past habitat loss might have thereby declined and stabilized; but, the fraction of habitat so protected is currently unknown (Farjon 2013).

Remarkable Specimens

The only data I have seen are from a dendrochronology study by Carmona-Velasco et al. (2022), finding ages of up to 40 years.

Ethnobotany

There are no known uses (Farjon 2013, Adams 2014, Thomas 2019).

Observations

See the collection records on iNaturalist.

Remarks

The epithet means "like a small boat", a reference to the concave leaves (Gandoger 1910).

Citations

Adams, Robert P. 2014. Junipers of the World: The Genus Juniperus, fourth edition. Bloomington, IN: Trafford Publishing. 415 pp.

Adams, R. P., and A. E. Schwarzbach. 2012. Taxonomy of Juniperus section Juniperus: sequence analysis of nrDNA and five cpDNA regions. Phytologia 94:269–276.

Carmona-Velasco, J., García-Cervigón, A. I., and Casimiro-Soriguer, R. 2022. Population and reproductive structure of an endangered juniper from coastal pine forests. Journal for Nature Conservation 67:126178. doi:10.1016/j.jnc.2022.126178.

Farjon, A. 2013. Juniperus oxycedrus var. transtagana. The IUCN Red List of Threatened Species 2013: e.T16348802A16348883. https://www.iucnredlist.org/species/16348802/16348883, accessed 2022.12.21.

Gandoger, M. 1910. Notes sur la flore hispano-portugaise. Quatrieme voyage en Portugal; IX Bull. Soc. Bot. France 57:54-62. Available: Biodiversity Heritage Library, accessed 2022.12.21.

Thomas, P. 2019. Juniperus navicularis on Threatened Conifers of the World. https://threatenedconifers.rbge.org.uk/conifers/juniperus-navicularis, accessed 2022.12.21.