The Iturraran Botanical Garden extends along the slopes of the Iturraran hill, in the foothills of Mount Pagoeta, within the Natural Park of the same name. Its surface area is about 25 hectares and within it are some groves of native vegetation, especially mixed hardwood forest, with Quercusrobur as the dominant species. It is located in the municipal area of Aia, Province of Gipuzkoa, Basque Country, northern Spain, and is owned by the regional government, the Provincial Council of Gipuzkoa. It is located 25.5 km from Donostia-San Sebastián, 7.5 km from Zarautz and 90 km from Bilbao. It is part of the pre-coastal topography of Gipuzkoa. It has a network of 5 km of roads and its altitude is between 120 and 210 m.
A view of the Iturraran Botanical Garden, with the old farmhouse that houses the office of Pagoeta Natural Park
The weather is mild, with temperatures softened by the marine influence, but occasionally 40 ºC can be reached on days with south wind, mainly during summer. Winter temperatures rarely drop below –5 ºC, frosty days are very scarce and snow is rare. The last time the temperature dropped below 0 ºC was on February 28, 2018, the only day we had frost that winter.
Average annual rainfall ranges between 1500 and 1800 mm. The soil is predominantly clay, with a neutral pH, despite the fact that the base rock is limestone. The soils are heavily washed by precipitation.
The name Iturraran is pronounced Ee-too-rah-RAHN, with emphasis on the last syllable. There is no written accent on that syllable, which would normally be the case in Spanish, because it is a Basque name and accents are not used in Basque. The origin is unclear, but it refers to a fountain (iturri).
The first plantations at the Iturraran Botanical Garden date from winter 1986/87. At that time the land where the Botanical Garden stands were the pasture meadows of the Iturraran farmhouse, mowed every year to make fodder for cattle. The farmhouse, dating to the 18th century, had been acquired a few years earlier by the Provincial Council of Gipuzkoa (regional government of the Basque Country province) so as to install in it the offices of the Pagoeta Natural Park.
An aerial view of the Iturraran Botanical Garden
At first it was simply ornamental plantations, focusing on deciduous trees and shrubs with good autumn colors. Later it was decided to make an arboretum or botanical garden. In principle it was divided into 8 areas, in each of which a certain family of plants had a leading role. Thus area 1 was for Fagaceae, area 2 for Sapindaceae, area 3 for Leguminosae, area 4 for plants of Mediterranean climates, area 5 for Juglandaceae and other families, area 6 for Rosaceae, area 7 was a native oak forest (Quercus robur), and area 8 was for Gymnosperms.
Later plantings deviated from that distribution to a certain extent, as it has been necessary to distribute different species in the most convenient area for their needs, according to type of soil, exposure or slope. For example, a Quercus from Colombia could not be planted in the same area as one from northern Japan.
I have had the pleasure of managing the Botanical Garden from its beginnings until my retirement in 2012. Many of the Quercus species and some other genera have been collected by me on different trips through Mexico and Central America. At the moment I still dedicate a couple of days a week to supervising the Garden.
The native Quercus robur forest at the Iturraran Botanical Garden, in spring
With the exception of the Fagaceae, which we will deal with later, the main collections are:
Lauraceae, with around 100 species belonging to 15 genera: Apollonias, Beilschmiedia, Cinnamomum, Cryptocarya, Laurus, Lindera, Machilus, Nectandra, Neolitsea, Nothaphoebe, Ocotea, Persea, Phoebe, Sassafras, Umbellularia.
Sapindaceae, with about 200 species and cultivars, belonging to 7 genera: Acer, Alectryon, Dipteronia, Dodonaea, Koelreuteria, Sapindus, Xanthoceras.
Gymnosperms, with 263 species belonging to the families Araucariaceae (7 species of 3 genera), Pinaceae (148 species of 9 genera), Podocarpaceae (33 species of 11 genera), Cupressaceae (57 species of 19 genera), Sciadopityaceae (1 species of 1 genus) and Taxaceae (14 species of 3 genera).
Nothofagaceae, with 13 species from Chile, New Zealand and Australia.
Fagaceae constitute the main collection of the Iturraran Botanical Garden. Five genera are represented: Castanea (7 species), Castanopsis (12 species), Fagus (10 species), Lithocarpus (16 species), and Quercus (around 300 species).
The most interesting in our collection are the Castanopsis, Lithocarpus,and Quercus genera (in the latter, particularly the species from Mexíco and Central America and those of the Asian section Cyclobalanopsis). They are listed and mostly illustrated below. Selected images of plants from other genera and families can be found at the end of this article.
Castanopsis is a genus of the Fagaceae that has about 140 species, all of them from tropical and subtropical Asia, all of them typical components of the cloud forest. Many of these species had been included in the genus Quercus. They are evergreen trees, with leaves with a whole margin or, sometimes, serrated. Inflorescences usually unisexual, erect, in spikes or in panicles; the masculine flowers grouped in fascicles of 3–7, rarely solitary; female flowers solitary or in groups of 3–7 per cupule. The solitary cupules, rarely indehiscent, totally or partially covering the nuts; nuts 1–3 per cupule.
Castanopsis species are rarely seen in botanical collections. In Iturraran we can find:
Castanopsis carlesii (Hemsl.) Hayata (Quercus carlesii Hemsl.), from central and western China, Taiwan, and Vietnam.
Castanopsis cuspidata (Thunb.) Schottky (Quercus cuspidata Thunb.), from Japan and Korea.
Castanopsis delavayi Franch., from central and southeast China.
Castanopsis eyrei (Champ. ex Benth.) Hutch. (Quercus eyrei Champ. ex Benth.), from central and eastern China and Taiwan.
Castanopsis fissa (Champ. ex Benth.) Rehder & E.H.Wilson (Quercus fissa Champ. ex Benth.), from southeastern China Laos, Thailand and Vietnam.
Castanopsis sclerophylla (Lindl. & Paxton) Schottky (Quercus sclerophylla Lindl. & Paxt.), from south-central and south-eastern China.
Castanopsis sieboldii (Makino) Hatus., from Korea and Japan.
Castanopsis sp. from Myanmar.
Castanopsis tribuloides (Sm.) A.DC. (Quercus tribuloides Sm), from Assam, Bangladesh, south-central China, East Himalaya, Laos, Myanmar, Nepal, Thailand, Tibet, Vietnam, West Himalaya.
We also have three other unidentified species from Vietnam.
Lithocarpusis another exclusively Asian genus of the Fagaceae family and like Castanopsis very rare in botanical collections, many of its species were previously considered to belong to genus Quercus. They are trees, sometimes shrubs, evergreen. The inflorescences are more or less erect, they can be male, female, or with male and female flowers. The male ones are erect, simple or branched, with 3–7 flowers. The female flowers are solitary or in groups of 1-}–3. The cupules are grouped in cymes on the rachis of the inflorescence, many of them abort before maturity, totally or partially covering the nut, only one nut per cup. There are approximately 340 recognized species. They can be found in Assam, Bangladesh, Borneo, Cambodia, north-central China, south-central China, south-eastern China, East Himalaya, Hainan, Japan, Java, Laos, Malaya, Maluku, Myanmar, Nansei-shoto, Nepal, New Guinea, Philippines, Sulawesi, Sumatra, Taiwan, Thailand, Tibet, Vietnam.
Lithocarpus pachyphyllus (Kurz) Rehder var. pachyphyllus (Quercus pachyphylla Kurz), from Assam, Bangladesh, south-central China, East Himalaya, Myanmar, Nepal, Tibet.
Lithocarpus pachyphyllus var. fruticosus (Watt ex King) A. Camus, from south-central China, Myanmar.
Lithocarpus shinsuiensis Hayata, from Taiwan.
There are also other unidentified species, from Burma and Vietnam.
Quercus is the genus best represented in the Iturraran Botanical Garden, with some 300 species and many hybrids. The vast majority of species from Europe, North America and Asia are represented (excluding section Cyclobalanopsis), for this reason we cannot speak extensively about this genus and we will limit ourselves to the Cyclobalanopsis species and the Quercus of Mexico and Central America.
Cyclobalanopsis is currently considered to be a section in subgenus Cerris, although Flora of China treats it as a separate genus. They are evergreen trees and sometimes shrubs, with about 150 species from tropical and subtropical Asia, due to their origin they are thought to be not very rustic and are found in few collections. In Iturraran we can find the following species:
Quercus acuta Thunb., from south-eastern China, Japan, Korea, Taiwan.
