Sessions / Chairman and key note speaker

1) Taxonomy, evolution / Alan Forrest

Recent studies place the genus Dracaena in the family Asparagaceae subfamily Nolinoideae. DNA analyses showed that Dracaena clade includes ancestral genus Pleomele Salisbury, Chrysodracon (Jankalski) P.-L. Lu & Morden and Sansevieria. The dragon tree group of Dracaena doesn’t create monophyletic clade on tree of all Dracaena members. DNA analysis shows that differences in arborescent Dracaena habit are homoplasious so arborescence could have arisen independently during evolution of Dracaena genus repeatedly. Thus, in taxonomy and evolution of Dracaena and relative genus are many open questions and aim of this session is to find answers.

2) Morphology and anatomy / Joanna Jura-Morawiec

This session aims to provide an overview of the morphological and anatomical characteristics of dragon trees, such as e.g., shape/structure modifications caused by environmental factors, structure-function relationships at the organ/tissue level, or species-specific characters. Any research relevant to the topic is welcome, including current and potential methodological (sampling, sample preparation) and analytical approaches (image analysis, cell measurement) that might broaden our understanding of the biology of dragon trees at the morphological and anatomical level.

 3) Eco-physiology / Nadezhda Nadezhdina

Physiology of dragon trees was till now poorly studied. The lack of studies on monocot functionality is probably due to the lack of commercial importance of arborescent monocots and their remoteness from major academic institutions. Another reason of lack of such studies could be that vascular system of arborescent monocots is more complicated than in dicots. Sap flow, water uptake from mist and fog, photosynthesis and other physiological processes were poorly studied in both, laboratory and in situ conditions. Especially in situ investigation for long-term period is requested to understand the way, how Dracaenas survive in their harsh environment.

4) Distribution, ecology / Michele De Sanctis

Population inventory is missing especially for African and Arabian species. The knowledges about detailed distribution of individual species and their population structure are urgently needed because most of species are strongly threatened. There is no information published regarding the growth dynamic and age estimation of other dragon tree species except D. draco and D. cinnabari. Growth of D. draco is described based only on a few specimens, mostly biggest and oldest, young measured trees were cultivated out of the area of origin, information is sketchy. Only growth of D. cinnabari was investigated in situ on sufficient amount of trees, nevertheless information is incomplete. For example, we still don´t know methods of age estimation and growth dynamics of the stem before first flowering. Poor information are known concerning the water uptake from horizontal precipitation

5) Ethnobotany, history of resin harvesting / Julian Jansen Van Rensbug

The first reference to the actual origins of dragon’s blood, however, comes from the Periplus Maris Erythraei (mid-first century BC), which mentions that Arab, Indian and Greek settlers were sailing to Soqotra to trade in tortoise shell, aloes and Indian cinnabar. A Fourier Transform Raman Spectroscopicity study of dragon’s blood resins from a number of geographical locations found that the original source of this resin in antiquity was from the Dracaena cinnabari of Soqotra. This would certainly seem to indicate that Soqotra was not only a primary source of dragon’s blood in antiquity, but that it was being intensively harvested. Whilst the trade in dragon’s blood resin continued throughout the medieval period there were an increasing number of alternatives from different geographical locations such as the Canary Islands and the East Indies. This demand continues into the seventeenth century, with ships of the East India Company reportedly having carryed out a small trade in aloes and dragon’s blood. The importance of this trade locally is reflected in a nineteenth century account, which mentions that the Sultan not only controlled much of the trade but also derived his third highest source of revenue from dragon’s blood resin, after ghee and aloes. Whilst the trade in dragon’s blood is likely to have formed an important part of Soqotra’s economy for several centuries little is known about how it was managed or harvested. To determine this, it was necessary to combine the archaeological, historical and ecological evidence, which demonstrates that there was likely to have been an intensive island-wide harvesting and management strategy for of Dragon’s Blood from at least the mid-first century AD. Similarly, Dracaena cochinchinensis and relative Asian species played important role in Chines region from ancient time. Dragon trees across all area of distribution are used not only for resin production but also for many other purposes, e.g. as fodder, building material, fuel, medicine for humans and livestock, a decorative paint, a cosmetic, to repair pottery, for the manufacture of cordage and other artefacts or for beehives production.

 

6) Chemical composition of resin, medical use / Wenli Mei

Dragon’s blood is the red resin produced as secondary metabolites by the xylem. Dragon’s blood derived from Dracaena species is a phenolic resin, with chemical content based on i) Flavonoids (Chalcones and Dihydrochalcones, Flavanones and Flavans, Polymeric Flavonoids, Chromogen Ketones), ii) Terpenes, Steroids and Steroidal Saponins, iii) Lignans, iv) Phenolic Constituents, v) Other Ingredients (alkanes, olefins, acids, esters, aromatic constituents). The main chemical constituent of this kind of dragon’s blood are flavonoids. Many flavonoids, chalcones, chalconepolymers, stilbenes, sterol saponins have been isolated in dragon’s blood. These compounds have been used for centuries in traditional medicine and possesses antimicrobial, antiviral, antitumor, antihemorrhagic, immunomodulatory, antiulcer, analgesic, antioxidative, antiinflammatory and antimutagenic activities. Chemical content of D. cinnabari, D. draco and D.cochinchinensis resin is well-recognized, however, there is a lack of studies focused on volatiles produced by resin of other dragon tree species.

7) Species-specific relationships (Dragon trees as habitat) / Raquel Vasconcelos

Dragon trees serve as the umbrella and flag species of communities that co-create in regions of their occurrence. Mostly endemic dragon tree species are habitats for also many others often endemic organisms: reptiles, insects, birds, mosses, lichens, etc. Dragon trees are also labelled as nurse trees providing a suitable environment for many plant species and keeping a high level of biodiversity. The importance of dragon trees as habitat isn´t well described in many regions of occurrence!

8) Threat, nature conservation / Alan Forrest

Most arborescent species of Dracaena genus are endemic, thus endangered and listed in Red List in global or national levels. In the case of the dragon tree, the widespread lack of regeneration and the consequent decline in population densities have been well documented and clearly indicate the high threat of these iconic species. The main reasons for population decline are overgrazing and following ecosystem aridification, long-term climate oscillation, cutting of leaves, dragon blood harvesting, mine extraction and road construction, these effects can be intensified by global climate change in the last years. The fragmentation and isolation of dragon tree populations could cause the bottlenecks effect. Effective conservation measures for dragon´s blood tree are thus urgently needed, but designing them requires a better understanding of the species’ ecology and population dynamics.