Aquilegia Paui

''Aquilegia paui'' is a species of perennial flowering plant in the genus ''Aquilegia'' (columbines) in the family Ranunculaceae. The species has an extremely limited range, narrowly endemic only to the mountains of Ports de Tortosa-Beseit, a massif in the Province of Tarragona in Catalonia, northeastern Spain. Due to a herbarium filing error, and the absence of observations of ''A. paui'' from 1920 until 1999, the species was long considered a subspecies or synonym of ''Aquilegia vulgaris''.

Growing up to tall, the species blooms in May and June. The flowers are bluish-purple with pale or whitish petals. The species has a small population that, as of 2011, numbered about 2,000 individuals spread across four subpopulations. Human activity, predation by the native Southeastern Spanish ibex, and poor genetic diversity have been cited as risks to the continued survival of ''A. paui''.

Description

''Aquilegia paui'' is a perennial herbaceous flowering plant in the genus ''Aquilegia'' (columbines) in the family Ranunculaceae. The species possesses a rootstock that can be either simple or branching. From this, one or two aerial stems will grow each year. The stems, which are glandular and pubescent (covered in small hairs), grow between and tall. The pubescence increases in density towards each stem. The basal leaves (leaves stemming from the base of the plant) are to long and borne on long petioles of to long. They emerge in rosettes and once- or bi-ternate (spreading into one or two leaflets with three lobes). The leaves are glabrous (hairless) on their topsides. On their bottom sides, they are glaucous (blue-grey) and can be either glabrous or more rarely glandular-pubescent. There are one to three cauline leaves (leaves attached to the aerial stems) on each stem. The cauline leaves are smaller than the basal leaves.

The inflorescences of ''A. paui'' are bracteate. Each inflorescence bears one to three flowers. The species generally blooms between mid-May and early July, though flowers have been observed in August. The flowers measure between and in diameter. ''Aquilegia'' flowers typically each have five sepals, five petals, and five carpels. Each petal has two portions: a broad portion called a ''blade'' or ''limb'' that projects forward and an elongated base that forms a structure called a ''nectar spur'' that projects backward and contains nectar. On ''A. paui'', most flowers only possess between one and four petals and nectar production is reduced. The flowers are variable in color, with sepals and petals ranging from blue-violet to whitish with green portions. The sepals are shorter than the petals, measuring to long and to wide. The shape of the sepals can be lanceolate or ovate-lanceolate. The corolla (arrangement of the petals) measures between and in diameter, with the petals positioned in a cylindrical or obconical manner.

''Aquilegia'' are capable of both sexual reproduction and autogamy (self-fertilization). ''A. paui'' is hermaphroditic (possessing both male and female reproductive organs), and is presumed to be primarily autogamous. Fruiting on ''A. paui'' occurs in June and July, with fruit taking a month to ripen. On each fruit, there are one to five glandular-pubescent follicles that are to long. The black, shiny seeds are arranged in rows within the follicles. ''A. paui'' plants produce significant quantities of seeds. The species does not appear to reproduce effectively through seed. Few plants fruit each year and at least 30% of fruits are lost before reaching maturity due to predation. Instead, ''A. paui'' seems more proficient at reproducing through the spreading of its rhizomes.

Ecology

Despite its historical taxonomic subordination under the species ''Aquilegia vulgaris'', substantial morphological differences distinguish the two species, notably that ''A. paui'' has fewer flowers and follicles, as well as smaller leaves. The species ranges overlap in Ports de Tortosa-Beseit. There, ''A. paui'' favors rockier areas near cliffs and away from other vegetation, while ''A. vulgaris'' populates moist, shady areas.

A 2011 paper described a study conducted in 2006 and 2007, in which no insects visited the observed ''A. paui'' flowers during any of the 74 15-minute-long daytime observations periods. The study recorded 102 insect visits in 67 observation periods for the observed ''A. vulgaris'' flowers nearby. The same study determined that the exposure of ''A. paui'' flowers to pollinators or solely to spontaneous self-fertilization did not impact the number of mature seeds produced per flower. In ''A. vulgaris'', seed production was improved by open-pollination.

Within a short period, the genus ''Aquilegia'' has evolutionarily radiated. The evolution of speciation in morphological and biological differences has occurred more rapidly than genetic distinctions, permitting hybridization where cross-pollination of ''Aquilegia'' species is possible. In the case of ''A. paui'' and ''A. vulgaris'', the likelihood of such cross-pollination is low: pollinators frequenting ''A. vulgaris'' are unlikely to visit ''A. paui'', as the latter plants are isolated and offer less nectar.

The native Southeastern Spanish ibex, a species of goat, frequently eats ''A. paui''. The goats eat basal leaves, flowering stems, and fruit from the plant. A personal observation assessed that goats consumed 30% of ''A. paui'' fruit before they reach maturity. As with other ''Aquilegia'', consumption by mammals is not considered a component of ''A. paui''s reproductive diffusion. Conservation of the goat might endanger the survival of ''A. paui'' due to overgrazing.

Taxonomy

''Aquilegia paui'' was given its taxonomic name by the Catalan botanist Pius Font i Quer in 1917 in the Catalan-language journal ''Anuari'' of the Junta de Ciències Naturals de Barcelona. He first described the species in 1920 in the journal ''Treballs del Museu de Ciéncies Naturals de Barcelona''. Font Quer produced an exsiccata, the ''Flora Iberica Selecta'', from biological specimens he had collected. However, within this exsiccata, specimens of ''A. paui'' and ''A. vulgaris'' collected around ''A. paui''s type locality of Ports de Tortosa-Beseit were mistakenly mixed.

From 1920 until 1999, ''A. paui'' was not observed in the wild. Due to the mixing of the herbarium specimens, a 1984 flora of Catalonia and the 1986 ''Flora Iberica'' both reevaluated the plant as subspecies of ''A. vulgaris'' under the name ''A. vulgaris'' subsp. ''paui''. An earlier 1971 work had synonimized the taxon with ''A. vulgaris'', a decision the Italian botanist Enio Nardi later said was made "for no apparent reason".

After an extended period without scholarly interest, ''A. paui'' became the subject of attention following its 1999 rediscovery in the Parc Natural dels Ports, near the sites of the earlier collections. The taxon was tentatively reaccepted as a species in 2001 and 2003 based on this rediscovery. A 2007 study reconfirmed ''A. paui'' as a species following the revelation of the mistakes with Font Quer's herbarium specimens. A herbarium specimen collected in 1917 was selected to serve as the lectotype in 2014.

, provisional assessments place ''A. paui'' within a species complex spanning France and Iberia. This complex, headed by '' Aquilegia viscosa'', also includes '' Aquilegia montsicciana'' and '' Aquilegia zapateri''. Of these, ''A. paui'' possesses the smallest flowers and petal limbs. These species are part of a broader complex of blue-flowering European ''Aquilegia'' that includes ''A. vulgaris''.

Etymology

The word '' columbine'', the common name for species in the genus, derives from the Latin word ''columbinus'', meaning "dove", a reference to the flowers' appearance being similar to a group of doves. The genus name ''Aquilegia'' may come from the Latin word for "eagle", '' aquila'', in reference to the petals' resemblance to eagle talons. A more likely etymology for ''Aquilegia'' is a derivation from the Latin ("to collect water"), '' aquilegium'' (a container of water), or ("dowser" or "water-finder") in reference to the profusion of nectar in the spurs. The species is named for the Spanish botanist Carlos Pau y Español.

Distribution

''Aquilegia paui'' is found in the Province of Tarragona in Catalonia, northeastern Spain, on the Iberian Peninsula, where it is extremely narrowly endemic. , the entire species comprised a single population across four subpopulations, with the largest of the three surveyed subpopulations numbering 300 individual plants. In 2011, the total population was about 2,000 individual plants. Each subpopulation was within a few kilometers of each other in the Ports de Tortosa-Beseit massif near its highest peak, Mont Caro. The total area covered by each subpopulation combined measures less than .

The area where ''A. paui'' grows is mountainous. The species prefers rocky outcrops and generally populates shady, north-facing calcareous cliffs and screes. It can be found within a narrow range of elevations, with plants found between and above sea level.

European species of ''Aquilegia'', particularly ''A. vulgaris'' and '' A. alpina'', have been present in gardens for hundreds of years. In 1946, the American botanist Philip A. Munz reported that the species was not in cultivation. In 2011, a study predicted that cultivation of the species would be difficult due to poor ability of ''A. paui'' to reproduce by seed.

Conservation

, the Royal Botanic Gardens, Kew's Plants of the World Online evaluated the extinction risk for ''Aquilegia paui'' as "threatened" with high confidence, while the IUCN Red List has not provided a conservation status. Due to its limited geographic range and rarity of reproductive plants, studies in 2001 and 2003 appraised ''A. paui'' recommended an IUCN assessment of critically endangered.

In 2011, a conservation assessment in ''Oryx'' recommended that the IUCN classify ''A. paui'' as an endangered species. The paper was based on 20 surveys performed within the species's range between 1999 and 2008, and appraised the plant as highly vulnerable. Among the risks to the species listed by the study were low genetic diversity, limited geographic distribution, encroachment by humans, and fires. The study suggested that construction of telecommunication facilities on Mont Caro may have been responsible for the drop in plants in one subpopulation between 1999 and 2007. The study argued that the active habitat conservation and ''ex situ'' conservation (preservation away from the natural range) would be necessary to prevent the extinction of ''A paui'', but would be difficult due to the poor reproductive success of ''A. paui'' by seed. It also proposed that individual subpopulations should be supported such that they each sustain 250 reproductive individuals. The study noted that efforts to conserve the endemic Southeastern Spanish ibex could interfere in conserving ''A. paui'', as the ibex may have overgrazed on two ''A. paui'' subpopulations.

Using the 2011 ''A. paui'' conservation assessment as an example, the Australian botanist Stephen Hopper emphasized the role of taxonomic understanding in plant conservation. Hopper pointed to the heightened risk faced by "poorly known endemics" and quoted the assessment's conclusion that ''A. paui'' was an example of plants "facing extinction in anonymity because their taxonomic status has been misunderstood or overlooked".

References

{{Portal bar, Biology, Plants, Spain

paui
Endangered plants
Endemic flora of Spain
Plants described in 1920
Taxa named by Pius Font i Quer