Dragon tree

Another Russian name used in relation to this species at the beginning of the 20th century is “dragon” ^[9] .

In addition to the species Dracaena draco , a dragon tree is also called some other species of this genus that secrete a blood-red resin - Dracaena cinnabari and Dracaena ombet ^{[2] [10]} .

The natural range of the species covers part of Macaronesia ( Canary Islands , Madeira ) ^{[10] [11]} and Morocco ^[11] . Plants in nature are mostly found on rocky cliffs of volcanic origin at an altitude of not more than 500 meters above sea level ^[10] , usually in hard-to-reach places, while populations are usually small and scattered ^[12] . The dragon tree bears fruit quite abundantly, but its natural regeneration is very weak - both due to the fact that few seeds germinate, and because of the domestic animals that eat the newly emerged plants, and because of the pickers that the plants dig up ^[12] .

It is found in the Canary Islands in Homer , Gran Canaria , Palma and Tenerife ^[12] ; dragon tree is distributed here at an altitude of 100 to 400 m above sea level; in valleys, the plant is often cultivated ^[6] . On the island of Madeira , according to data from the early 1980s, the plant is rare, small trees can be found only on the coast on inaccessible rocks ^[6] ; previously also found on the island of Porto Santo , part of the Madeira archipelago ^[12] .

As a naturalized plant, the dragon tree is found in Cape Verde ^[11] (the islands of Brava , Sao Vicente , Sao Nicolau , Santo Antan , Fogo ^[12] ). Here, the plant population is very low, individual specimens were preserved only on the mountain slopes among xerophytic vegetation, while adult plants are significantly inferior in size to those in the Canary Islands: for example, centenary plants have a height of only about 5 m . In the mid-20th century, the main reason for the decrease in the number of dragon trees in Cape Verde was the felling of young trees, as a result of which the plant disappeared completely on some islands of the archipelago ^[6] (in particular, there is an assumption that it disappeared on the island of Santiago ^[12] ).

The information available in some sources on the growth of this species of dracaena in Somalia and Ethiopia ^{[2] [10]} by the GRIN project, however, is not confirmed ^[11] .

Slow - growing ^[4] tree-like plants up to 20 m high . The trunk is strong, silver-gray in color ^[10] , reaches 4.5 m in diameter at the base ^[3] ; has a secondary growth in thickness ^[2] , while the growth occurs not due to the activity of cambium (as in gymnosperms and dicotyledons ), but as a result of the activity of meristematic cells located on the periphery of the trunk ^[13] . A simple trunk begins to branch over time. Plants do not form annual rings , so it is sometimes impossible to determine age ^{[2] [10]} . With age, aerial roots begin to form in dragon trees ^[14] . When an incision is made in the bark, sticky juice (the so-called “dragon blood”) begins to stand out from the trunk, which turns red in the air ^{[2] [10]} .

Crohn's umbrella . The leaves are hard, leathery, linearly xiphoid, bluish (grayish-green) in color ^{[3] [10]} , length from 45 to 60 cm ^[3] , are gathered in dense bundles at the ends of branches ^[2] (the so-called “apical rosettes” ^[13] ). The width of the leaves is from 2 to 4 cm in the middle of the plate, they are somewhat narrowed to the base and pointed to the apex, have prominent veins ^[3] .

The flowers are small, subtle ^[4] , bisexual ^[2] , actinomorphic , in bundles of 2-4 ^[15] . The perianth is simple, corolla-shaped ^[15] , consists of six non-fused leaflets ^{[16] [15]} . Plants usually begin to bloom at the age of 8 to 11 years , but in some trees the first flowering is observed much later - at 25-30 years . By the time of the first flowering, plant trunks reach several meters in height and become bare, while scars from fallen petioles are noticeable on them. After the first flowering, the nature of the trunk growth changes in Dracaena draco : it begins to grow rather quickly (by 2-3 cm per year ) in diameter, while the scars from the petioles disappear; in addition, branching begins at the top of the trunk. The plant blooms not every year, but once at about 14-17 years ^[14] . Flowering occurs in the summer ^[4] .

The fruit is an orange berry ^{[2] [4]} . The fruits are edible, similar in taste to cherries ( Prunus avium ) ^[12] .

It was previously believed that the life expectancy of some plants of this species reaches 5-6 thousand years ^[2] ; according to modern concepts, the age estimate of old dragon trees was greatly overestimated ^[14] .

Since ancient times, the dragon tree has been the source of the so-called “ dragon blood ” (“dragon blood” ^[12] ) - a resinous juice of bright red color that is secreted in plants by incision of the bark (also in felled trees) ^{[14] [12]} . Dragon blood is traditionally obtained by the counting method ^[14] .. It has no smell, no taste, it is soluble in acetic acid and other organic solvents . Its melting temperature is 70 ° C; at 210 ° C, it begins to decompose ^[17] . It is used in folk medicine and for tinting wines, as well as for the manufacture of varnish for metal surfaces ^[14] . It contains the pigments dracocarmine and ^[14] .

Dragon Blood was discovered in prehistoric funerary caves in the Canary Islands; the Guanches , the indigenous population of the islands, used it, presumably, for embalming ^[14] , and also, possibly, used it in magical rites ^[12] . The Guanches considered the tree sacred, and draconian blood was used for medicinal purposes.

Leaf fibers are used for weaving baskets and other products ^{[10] [15]} . The dracaena leaf tissue contains elastic fibers that are used to make brushes.

Dracaena draco is cultivated as an ornamental plant in open ground (primarily in the Canary Islands and Cape Verde ) ^[11] ), as well as an indoor plant . In a culture, it easily propagates both by seeds and vegetatively by apical cuttings ^[3] . It is a very hardy plant, but it is not cultivated too often due to insufficient decorativeness ^[15] .

Unlike most other cultivated green leafy species of dracaena, which can be kept only in warm greenhouses, this species can be kept both in warm greenhouses and in cold ^[3] . In open ground, cultivation is only possible in areas belonging to frost resistance zones 10 or 11 (that is, the minimum temperature that plants can withstand is minus 1 ° C ) ^[4] .

One of the most famous canary dragon tree specimens grew in the northwest of Tenerife near Icod de los Vinos ^[6] . This plant has been known since the discovery of the island in 1402. Its trunk was conical in shape and was empty inside. Locals considered the tree sacred, in the XV century there was an altar inside it ^[14] . The tree died from a hurricane in 1868 ^[6] , by this time its height was about 23 m , and the trunk circumference was 15 m (which corresponds to a diameter of about 4.8 m ). The traveler Alexander von Humboldt saw this tree in 1799 ^[14] , its height at that time was about 19 m , and its diameter was about 4 m ; Humboldt estimated the age of this tree at six thousand years, however, according to modern concepts, this plant was most likely no more than six hundred years old ^[14] . Beketov in the " Brockhaus and Efron Encyclopedic Dictionary " wrote about this tree (which he called the "Orotava dragon"), that it blossomed and fructified until its death ^[18] .

At the end of the 20th century, the largest plant of this species was a tree growing near the city of La Orotava , its height was 21 m , the trunk circumference was about 8 m ^[14] .

The first valid description of this plant species was published in September 1762 in the first volume of the second edition of Karl Linnaeus Species plantarum ^[19] . Linnaeus placed this species in the genus Asparagus , while in the description after the generic name, he put a question mark. As the “trivial name” ( species epithet ), Linnaeus chose the word draco , which is given in the text as part of the name Draco arbor (from the Latin - “Dragon Tree”), used in relation to this plant by Karl Klusius in Rariorum plantarum historia ( 1601) and Caspar Baugin in the work of Pinax Theatri Botanici (1671). In accordance with the sexual classification system used by Linnaeus in the Species plantarum , the species was assigned to class VI (Hexandria, “Six-stamens”), the order of Monogynia (“Single-pedigree”) ^[20] .

In the second volume of the 12th edition of his work “ System of Nature ” published in October 1767, Linnaeus reclassified the plant by placing it in the genus Dracaena ^[21] .

The dragon tree is one of the species of the genus Dracaena (in total this genus includes more than one hundred species ^[22] ). According to Germplasm Resources Information Network (2018), the Dracaena genus belongs to the Nolinoideae subfamily of the Asparagaceae family ^[11] . The systematic position of this genus was extremely unstable for many years: it was considered as a part of the Agavaceae , Iglitsovye ( Ruscaceae ), Lily-of-the-valley ( Convallariaceae ), Liliaceae ( Liliaceae ) families — or they were allocated to their own Dracaenaceae ( Dracaenaceae ) ^{[23] [ 24]} .

Synonyms

According to The Plant List (2013) database, the following names are included in the synonymy of the species ^[25] :

• Dragon Tree / B. N. Golovkin // Atmospheric Dynamics - Railway Junction. - M .: Great Russian Encyclopedia, 2007. - P. 320. - ( Great Russian Encyclopedia : [in 35 vols.] / Ch. Ed. Yu. S. Osipov ; 2004—2017, vol. 9). - ISBN 978-5-85270-339-2 .

• Belousova L.S., Denisova L.V. Rare plants of the world. - M .: Forest industry, 1983.- 344 p. - 20,000 copies.
• Biological Encyclopedic Dictionary / Ch. ed. M.S. Gilyarov ; Editorial: A.A. Baev , G.G. Vinberg, G.A. Zavarzin , etc. - M .: Sov. Encyclopedia , 1986.- S. 183.- 831 p. - 100,000 copies.
• Dracaena // Botany. Encyclopedia "All plants of the world": Per. from English = Botanica / ed. D. Grigoriev et al. - M .: Könemann, 2006 .-- S. 313-314. - 1020 s. - ISBN 3-8331-1621-8 .
• Dragon Tree // Animals and Plants. Illustrated Encyclopedic Dictionary / Scientific. ed. Editions T. M. Chukhno. - M .: Eksmo, 2007 .-- S. 358-361. - 1248 s. - 5,000 copies. - ISBN 5-699-17445-1 .
• Ivanina L. I. The Dracaenaceae family (Dracaenaceae) // Plant Life : in 6 volumes / ch. ed. A. L. Takhtadzhyan . - M .: Enlightenment , 1982. - T. 6: Flowering plants / ed. A. L. Takhtadzhyana. - S. 169-177. - 543 p. - 300,000 copies.

• Linnaeus C. asparagus // Species plantarum , exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas: [ lat. ] . - Editio secunda, aucta. - Holmiae : L. Salvius, 1762. - Vol. I. - S. 448-451. - [i-xvi], 1-784 s. - DOI : 10.5962 / bhl.title . 111179 .