Centaurea del Ibérico
This species of the Compositae family was discovered by the botanist Carlos Pau, who sent a letter to his disciple, the pharmacist Benito Vicioso, describing it for publication in 1906. The master´s generosity was acknowledged and appreciated by the disciple.
Distribution
It is endemic to the Iberian System, where it is found in more or less continuous populations. It is endemic to the north-west of Spain, inhabiting the area where the provinces of Zaragoza, Teruel and Guadalajara converge.
Habitat
It lives in scrubland at an altitude of 500 to 1200 metres. It is found in various types of soil, including siliceous, clayey, and even gypsum-rich substrates, rarely on limestone soils. Its habitat includes rocky outcrops, forest clearings, roadsides, and road verges. It has remarkable capacity for colonisation, allowing it to thrive in disturbed environments. It blooms between June and July, producing approximately a dozen flower heads, each containing an average of 24 seeds. These seeds are dispersed by ants or carried by water, typically over short distances. The seeds usually germinate in autumn.
Conservation
Nineteen population clusters have been identified, with no significant distances between them, leading to the population being regarded as single entity. The main threats to the species are competition with natural vegetation, agricultural and livestock activities, mining and quarrying. Seeds from this species are stored in various Spanish germplasm banks.
Images descriptions
The fruits of Centaurea pinnata are known as achenes, which are arranged on the inflorescence called a capitulum. When mature, the capitulum opens to facilitate seed dispersal.
The optical microscope image provides a close-up of the apex of the achene, revealing a double crown of scaly hairs, known as the pappus. The outer pappus consists of multiple rows of uneven, linear, serrated scales, while the inner pappus forms a single row of shorter, smooth scales that are only lacerated or serrated at the apex. In addition, a dense pilosity is visible on the yellowish surface of the achene.
The scanning electron microscope image shows a complete achene with its pappus, and the surface of the achene is pilose and reticulated. It is cuneiform in appearance, and has a concave attachment scar, where a funicular aril, also called an elaiosome, is located. This structure aids in seed dispersal by insect.