Category: Biodiversitat

This October, a very special process took place at the Marimurtra Botanical Garden on a specimen from the cycad collection: the artificial pollination of an individual of Dioon merolae. This species is native to southeastern Mexico, in the states of Oaxaca and Chiapas, where it lives in pine and oak forests. Like many species of this genus, it is threatened (Vulnerable category, according to the IUCN Red List) and its trade is restricted under the international CITES convention. Dioon belongs to one of the oldest groups of seed plants still living on the planet, which already existed more than 250 million years ago, before the age of the dinosaurs.

Until now, it had not been possible to confirm whether this specimen was male or female, as it had not produced any cone. This year, however, the appearance of the female cone has made it possible to verify that it is a female plant and, therefore, to attempt artificial pollination in order to produce seeds.

To make this possible, Iván Soto, head of the cycad collection at Marimurtra, used the pollen from a male specimen found in Marimurtra. After collecting the male cone and gently tapping it over a tray, a sufficient amount of pollen was obtained. This was mixed with water to facilitate its application and introduced into the female cone, where the ovules are located.
Unlike what happens in its natural habitat, where certain insects are responsible for pollination, in the Garden this process was carried out manually to increase the chances of successful fertilization.

Now we must wait. The seed maturation process is very slow: it can take about six months or more until the female cone opens and allows the collection of mature seeds. Once collected, they must be cleaned and stored for several additional months so that the embryo can finish maturing. If all goes well, in about a year we will know whether fertilization has been successful. Artificial reproduction is a delicate process that requires patience and care.

Cycads, such as Dioon merolae, are extraordinarily long-lived plants, hundreds of years old, and it has been estimated that, exceptionally, some could live for more than a thousand years. With this action, Marimurtra takes another step forward in the conservation and understanding of this fascinating group of plants, living witnesses to the evolutionary history of the Earth.

In Narberhaus Square, our exhibition of pumpkins is already on display once again. A showcase of varieties that surprises with the diversity of shapes, colors and sizes, and that reminds us how much this fruit has accompanied humanity throughout history.

This year we present 17 varieties from different genera —Cucurbita and Lagenaria—. The seeds, initially obtained from the cooperative Les Refardes, are now part of our own conservation cycle. The pumpkins sown in March come from the previous year’s harvest at Marimurtra. Among the most unique specimens we find the “Sicilian snake” (Lagenaria siceraria longuissima), the giant pumpkins of Cucurbita maxima, or the delicate varieties of Cucurbita moschata, such as the “Violín” or the “long of Gironella.”

Beyond the shape: the value of conserving varieties

Pumpkins belong to the family Cucurbitaceae, with more than 120 genera and around 900 species. Cultivated for about 15,000 years, they have been used for food, medicine and even as everyday utensils, especially in the case of bottle gourds (Lagenaria siceraria).

Preserving local varieties is key to keeping this diversity alive. In times of globalization and monoculture, these collections remind us of the value of an agricultural heritage that must be preserved.

A curiosity this year: hybridizations

This year we have detected that some pumpkins from Marimurtra have undergone hybridizations unintentionally. We do not know exactly which species have crossed, but specimens have appeared with traits that combine characteristics of different varieties and that, therefore, do not correspond to the original species.

Why does it happen?

Pumpkin plants belong to the family Cucurbitaceae, with species that are very close and often compatible with each other. This means that when they receive pollen from another variety —carried by the wind, insects or other animals—, hybrids can be generated naturally. The proximity between plants and the coincidence of flowering make this exchange even easier.

This hybridization phenomenon is not negative in itself, as it can give rise to new forms and possibilities. However, when the goal is to conserve specific local varieties, it must be monitored: if not properly controlled, some characteristic traits may be diluted or eventually disappear.

Come and see them!

The exhibition can be visited throughout the autumn in Narberhaus Square, in the second garden of Marimurtra. The goal is to showcase agricultural biodiversity and highlight the importance of conserving traditional varieties.

When you look at it for the first time, it seems straight out of a science-fiction movie. Its corolla is large, strange, and full of details that look as if designed by an alien mind. But it is not a creature from another planet: it is a plant, and its ingenious pollination mechanism is as surprising as it is effective.

A travelling and diverse genus

This plant belongs to the genus Aristolochia, which is cosmopolitan: we find it almost all over the world. More than 550 species have been described, some so small that they go unnoticed and others so large that they are true plant giants. The specimen we are focusing on is lianoid and climbing in habit and has cordiform leaves —heart-shaped— that bring a delicate contrast to the complexity of its flower.

A perfume with a double message

What for us is a citrus, fresh, and pleasant smell, for certain insects evokes quite the opposite: the smell of decomposing matter. This difference in perception is key to understanding its reproductive success: the pollinators, lured by the promise of a banquet, end up entering the flower… and can no longer escape.

The captivity mechanism

Once inside, small downward-oriented hairs (trichomes) prevent the insect from going back. During the first day, the flower is in female stage (protogyny): it is receptive and can receive pollen. Meanwhile, the pollen of the flower itself is not yet available.

On the second day, the plant shifts to male stage: it releases its pollen, which sticks to the insect’s body. When the hairs wither and the exit is free, the visitor unknowingly carries the load to the next flower.

Carnivorous or not?

Despite its appearance and its capture system, this plant is not carnivorous. The captured insects are not digested or used as a source of nutrients: they are merely victims of an ingenious reproductive trap.

A specialized ecological role

Many Aristolochia have very specific pollinators, such as small flies of the Phoridae family or other dipterans that feed on decomposing organic matter. This specialization ensures very effective pollination, but it also makes them vulnerable to the loss of those insects in altered ecosystems.

If this plant strategy has captivated you, imagine all the other stories hidden in the flowers of the Marimurtra Botanical Garden. Nature is, without a doubt, the best screenwriter.

In 2025, the Marimurtra Botanical Garden once again harvested an exceptional honey. A honey that is not only delicious, but also tells a unique story of biodiversity. After the retirement of Vicenç, this year we welcomed new beekeepers: brothers Àlex and Òscar, from Mels del Montnegre, a family business with a long history in artisan honey production and bee care.

In autumn, they brought the bees to Marimurtra’s 20 hives, located in a non-accessible but strategically chosen area, surrounded by the garden’s great plant diversity. During winter, the bees go into hibernation — that is, they reduce their activity to a minimum to save energy — and in spring, the intense activity begins: brood rearing and nectar collection, which they will transform into honey inside the hive.

This year’s figures are very positive: some hives reached populations between 80,000 and 90,000 bees, with an average honey yield of 30 kg per hive, and some reaching up to 40 kg. The amount of honey depends greatly on the number of bees in the hive and whether the colony remained stable or swarmed (meaning the colony became so large that part of the bees left with the queen to form a new hive).

This honey is special due to the wide variety of pollen collected by the bees: thousands of different plants contribute to its composition. One of the beekeepers joked that if we usually speak of “thousand flower honey”, in this case we might say it’s “ten thousand flower honey”.

To better understand the origin of this honey, a study of the pollen it contains is underway. This will help identify the plant species from which the bees collected the most abundant pollen and thus indicate which parts of the garden had the highest pollination activity. It will also give us a sense of the plants that contribute most to the honey’s flavour and aroma profile.

A taste of the land

Marimurtra honey is not just a local product. It is an expression of the territory, a natural synthesis of the garden’s biodiversity. Each spoonful contains aromas of Mediterranean, exotic, coastal and mountain plants, collected with patience and dedication by hundreds of thousands of bees.

This project not only offers us a unique honey, but also contributes to the pollination of the garden and strengthens Marimurtra’s role as a living, sustainable and biodiversity-connected space.

From May 15th to 18th, 2025, the fifth edition of the Spanish Flora Bioblitz (BFE) takes place — a citizen science event promoted by the Spanish Botanical Society (SEBOT) and the Botanical Institute of Barcelona. At the Marimurtra Botanical Garden, we’re joining as a collaborating entity, giving visibility to the project and informing our visitors via a poster at the garden entrance.

What is the Spanish Flora Bioblitz?

The BFE is an open activity for everyone, where participants head outdoors, observe and photograph wild plants while enjoying nature and learning about plant biodiversity. Observations are uploaded to the iNaturalist platform, where they are later identified with the help of a community of enthusiasts and experts.

This project was born out of concern about the growing disconnect between society and the plant world, and aims to make plants more visible in everyday life. It also promotes collaboration between citizens and researchers, bringing science closer to everyone.

How is Marimurtra involved?

At the Marimurtra Botanical Garden, we’re actively promoting the Bioblitz. We’ve placed an information poster at the garden entrance with instructions on how to download the iNaturalist app and join the project.

This aims to encourage discovery and awareness of the surrounding flora, and ensure that every visitor to the Garden has the opportunity to take part in this citizen science initiative.

How can you take part?

📱 Download the iNaturalist app on your phone.

📸 Photograph wild plants during the Bioblitz dates (May 15–18).

🌍 Upload your observations to the app. The botany community will help identify them!

🧠 Learn and contribute to building collective knowledge about plant biodiversity.

💡Make your visit to Marimurtra a contribution to science and nature conservation!

🔗 More information: biomaratonflora.com/participa

Did you know that cycads are among the oldest living plant species? These fascinating plants appeared over 300 million years ago—long before dinosaurs—and can still be found today in certain botanical gardens and natural habitats.

During the Jurassic period, cycads dominated vast areas of terrestrial vegetation. That era is often called the “Age of Cycads” in recognition of their ecological importance. These plants coexisted with the great Mesozoic reptiles and were an essential part of the landscape we associate with dinosaurs. Today, however, cycads are a highly threatened plant group.

Botanically, cycads are gymnosperms, like conifers and ginkgos. This means their ovules are exposed at fertilization, not enclosed in an ovary—hence the term “naked seeds,” a key feature of the group.

Another unique trait is that cycads are dioecious: each plant is either male or female, an unusual condition in the plant kingdom but highly relevant from a reproductive perspective.

Currently, around 300 species of cycads are known, grouped into two main families:

Cycadaceae, represented only by the genus Cycas, found in Southeast Asia, Oceania, and southeastern Africa.

Zamiaceae, with various genera, including:

• Dioon – Mexico and Central America

• Encephalartos – Africa

• Zamia – Central and South America, and the Caribbean

• Ceratozamia – Mexico

• Macrozamia and Lepidozamia – Australia

• Bowenia – Australia

• Stangeria – southeastern Africa

• Microcycas – Cuba

Many species are endangered due to habitat destruction. Slow growth, low reproductive rates, habitat specificity, and specialized pollination systems make cycads particularly vulnerable. According to the IUCN Red List (2022), 69% of cycad species are threatened (VU, EN, CR, or EW). Including near-threatened species (NT), the total rises to 80%.

One of Marimurtra’s key missions is to conserve, study, and expand living plant collections, supporting biodiversity preservation. Marimurtra’s outdoor cycad collection is one of the most significant in Europe, featuring 127 species in both public and cultivation areas—around 41% of known species worldwide.

Highlights include:

• Cycas: 30 of 160 species (18.75%)

• Dioon: 16 of 18 (88.8%)

• Encephalartos: 43 of 66 (65.2%)

To learn more, consult Col·leccions Marimurtra: 1. Cycads, by Pere Fraga and Iván Soto. The book includes an introduction, a detailed catalogue, and a map showing the locations of around 150 species you can see at Marimurtra. More info at marimurtra.cat.