Description & Remarks
An alien species of the Amaranth family (Amaranthaceae) that was recently rediscovered in Israel. Mars Smoli found it on 18.11.2018, many decades having passed since its last sighting in Israel (it was collected in 1949 by J. De’angelis in the fields of Mishmar ha-Negev). Until 2018, our only photograph of it had been taken by Lior Almagor in Tanzania in 2011. The new specimens were spotted at the edge of an untended lawn near a cowshed in the kibbutz of Tel Yosef in the Harod Valley (east of the Jezreel Valley). 5-6 clumps are growing in close proximity and are presently in different stages of growth, ranging in size from 20-50 cm to 100-180 cm. Subsequently, additional patches were found in the immediately surrounding area. The plant stands out due to its variable colorful inflorescences in their various stages of flowering and fruiting, a splash of greenish, yellowish, stramineous, and brown color against the verdure.
It is prostrate, 4-7 cm in height. The stem is 50 cm in length, branching, terete with a diameter of appx. 2 mm, bright green to dark brown, rooting at the nodes, flexuous in its bottom portion, hairy but with irregular concentrations of slightly curled hairs that are simple and not stiff. The branches and leaves are distichous (arranged in two opposite rows on two sides of the stem/branch and on the same plane). The stem’s internodes are very short, 2-4 cm in length, and grow even shorter closer to the branch tips. The short internodes give the plant a very compact appearance. The leaves are opposite and have a rigid texture. In most specimens, there is an observable difference in the size of the petiole and blade of the pair of nodal leaves. The leaves are ovate with entire margins and narrow slightly to a dull point or rounded apex, at which most have a small bristle. Their size varies: a large leaf can be 1.6-2.5 cm, not including the petiole which is 2-4 mm in length (different sources give a maximum size of 2.5-4.5 cm). The leaf is glabrate, with a ring of adpressed hairs at its margins, particularly on its lower portion and on the veins. Occasionally, the leaves are asymmetrical. The venation is pinnate, sunken on the upper side of the leaf and raised on the lower.
The flowers are bisexual, clustered in fascicles shaped like a capitulum or in oblong-ovoid spikes, with few or many flowers in each inflorescence. The inflorescences are axillary, occurring individually or sometimes in groups of 2-3 per leaf axil, and increase in size during ripening, reaching over 1 cm in length (in some sources even more) and 6-7 mm in width. The size of a small flower is 3-4 mm. All parts of the flower are papery, including the bract and two bracteoles. The bracteoles are transparent. The flower has five tepals that vary in size and shape. The two tepals that face away from the rachis are larger and end in a kind of bristle or awn that is about as long as a third of the entire tepal. This “bristle” is the continuation of the midrib or keel of the tepal, and it occasionally ends in an edge in the shape of an anchor. The bracteoles and other tepals also end in a bristle, which is shorter. At the base of the tepals are glochidate hairs. During ripening, all parts of the flower stiffen and become spiny. The color of the perianth, which is yellowish-greenish during flowering, turns stramineous and then brown. The flower has five stamens with golden anthers and a single pistil with a rounded stigma. The fruit is a compressed utricle typically hidden at the base of the inner tepals, with one gold or brown lenticular seed, about 1-1.5 mm in size. The dispersal unit is an indehiscent utricle together with parts of the perianth or the entire fertile inflorescence, which thanks to its spiny protrusions gets caught on clothes and animal fur, and stuck in shoes, tires, and agricultural equipment.
Reproduction: by seed, or by stem and branch cuttings that root after being cut.
Life-form: most sources classify it as an herbaceous perennial, although some describe it as an annual or short-lived perennial.
Distribution: broad. The plant originates from South America, and due to human introduction has become naturalized in North America, Asia, Australia, and both North and sub-Saharan Africa. It also appears occasionally in a number of European countries, such as Italy, Spain, and Germany. Closer to Israel, it has become naturalized in Egypt.
Habitat: a ruderal species that largely grows near areas of human activity, colonizing abandoned areas, roadsides, lawns, and parks. It is a pioneering species in areas of disturbance, and it can survive in different types of earth and diverse climates, excluding especially arid regions up to an elevation of 1300 m. In different parts of the world, including South Africa and various regions of Australia, it has been declared a noxious weed, and there are restrictions on or even prohibitions against growing and disseminating it, due to evidence of its spread to natural habitats and displacement of local flora, as well as the damage it causes to agriculture and people as a result of its spiny inflorescences and its toxicity to animals.
– Alternanthera pungens is very similar to the species Alternanthera caracasana (named after Caracas, Venezuela), which does not grow in Israel. The difference between them is the degree of their spinescence, as exhibited by the length of the sharp bristle at the apex of the external tepals: about a third of the tepal’s length in Alternanthera pungens and about a tenth of it in Alternanthera caracasana.
Distribution in Israel: Alternanthera pungens was collected one time in 1949 in an irrigated field in Mishmar ha-Negev. It was included in Flora Palaestina as having a typical South American distribution, as being adventitious in many countries and an accidental plant. In Michael Zohary’s A New Analytical Flora of Israel, it is described as alien, and in the new Analytical Flora of Eretz Israel (Feinbrun-Dotan and Danin, 1991) as a plant that did not seem to become naturalized.
– Another species of Alternanthera does grow in Israel: Alternanthera sessilis. It is native and grows in wet habitats. It is glabrous or glabrate, has lanceolate leaves, and its tepals are all of equal length and shape and are not spiny. This is in contrast to Alternanthera pungens, which thrives even in areas with little moisture, is hairy, and has spiny tepals of unequal size and shape.
The number of species in the genus Alternanthera varies widely according to the different sources, fluctuating between 80 and 200. The genus Alternanthera was first described by Pehr (Peter) Forsskål, one of Carl Linnaeus’ students, and the description was published posthumously in 1775. The species Alternanthera pugens was described in 1818 by Karl Sigismund Kunth, a German botanist who was one of the first Europeans to classify flora from the American continent.
Etymology: the name of the genus in Hebrew, Bitzan, refers to its wet habitat—bitzah (swamp). The name of the species in Hebrew, doqrani, refers to the spinescence of its inflorescence. The scientific name for the genus, Alternanthera, appears to refer to the fact that the flower’s stamens and staminodes are alternate (alternare). The scientific name for the species, pungens, is derived from the Latin verb pugnare, which means pricking or stinging.
The popular English name “khaki burr” refers to the khaki color of the spiny, fertile inflorescence.
Miriam Milo, 2018, translation by Daniel Tabak
- Hebrew with Vowels:
- בִּצָּן דּוֹקְרָנִי