This species first appeared before modern science in the herbarium of Karl Maximovich, in which he labelled the specimen as Rheum megalacarpum. One of the first Europeans to write about this species was the General Nikolai Ivanovich Korolkov, who was engaged in the conquering of Turkestan, and collected herbarium specimens of this plant there in the early 1870s. Another early collector was Johann Albert von Regel, who collected specimens of this species less than a decade later in the highlands throughout the region (Kazakhstan, Uzbekistan, Tajikistan). He called the plant R. ribes. Boris Fedtschenko later published R. megalacarpum in his 1915 work Растительность Туркестана, the Flora of Turkestan, but omitted a valid description. Agnia Losina-Losinskaja validly published the taxon in 1932 (the date in the publication itself is 1931) under its present name in the Известия Главного ботанического сада С.С.С.Р., also known as Bulletin du jardin botanique principal de l'U.R.S.S..[2]
Description
It has a single,[2] reddish,[1] leafless, branched stem 40–100 cm (16–39 in) tall, the base of which is compressed to (only) one side and is sulcate and is covered in minute warts or smooth. The lateral branches open to less than 45° to form a pyramidal-shaped inflorescence.[2]
The leaves are round, 50 cm (20 in) long and 60 cm (24 in) wide, and have a reniform base. The margin is slightly wavy and fringed in tiny needles. Each leaf has three extremely prominent veins which are lateral at the base and only fork towards the margin. The top of the leaf is smooth; the underside is warty along the veins. The petiole is short, shorter than half of the leaf blade, the top being warty, rarely glabrous (smooth).[2]
The flowers are congregated and have a long peduncle which is jointed at the base. The greenish tepals are subequal, around 3 mm (0.1 in) long and 1 mm (0.04 in) wide. The stamens are very long.[2]
The large, oval fruit are 20 mm (0.8 in) long and 15 mm (0.6 in) wide, and have lateral, cordate wings – dark reddish-black when ripe, red when immature, with a vein running near the edge. The tepals hug the fruit. The seed is ovoid, wrinkled and brown.[2]
Similar species
In her original 1932 description, as well as in her 1936 key in Komarov'sFlora SSSR, Losinskaja considers this species closely related and most similar to Rheum ribes,[1][2] the desert rhubarb of the mountains of the Middle East, in leaves and flowers,[2] classifying them both in the sectionRibesiformia.[1] It can be distinguished from this species by its much smoother stem, much shorter leaf petiole and pyramidal-shaped inflorescence.[2]
Hybrids
The natural hybrid Rheum × svetlanae from Central Asia is a hybrid of this species and R. compactum.[3]
It has been collected growing from approximately 1700 to 3200m in elevation in the Western Tian-Shan, from in the 1300 to 2000m in the Chatkalsky, from 2300 to 2600m in the Zarafshan Range, 1780m in the Hissar, and 3300 to 3700m in the Vakhsh region.[2]
In the Kaskasu Gorge of Kazakhstan it grows in the foothills in grass and gravel, unlike the sympatricRheum wittrockii which is found in more wooded settings.[10]
The caterpillars of the blue butterfly Callophrys titanus, which is found from southern Kazakhstan to Tajikistan and was described in 1998, have only been found to feed on R. maximowiczii. These caterpillars are myrmecophilous and are attended by a coterie of protective ants of the genus Lasius.[12]
^Czerepanov, Sergeĭ Kirillovich (1995). Vascular plants of Russia and adjacent states (the former USSR). Cambridge: Cambridge University Press. p. 412. ISBN978-0-521-45006-5.
^ abcdefVladimir Kolbintsev; Kurt Vickery (April 2013). The Tulips of the Tien Shan(PDF) (Report). Greentours Natural History Holidays. Retrieved 2 April 2019.