Plant Stories, chapter T (part 1)

עודכן: 6 באפריל 2014

July 23rd 2013


Chapter 20 part 1. And the scent of the saltbush on the water

I enjoyed defending a line in Naomi Shemer’s song “The Grove of Eucalyptus,” which says: "…and the scent of the saltbush on the water.” I copied my response to one of the critics of the line into the Hebrew page of the plant in my website. The critic claimed that Naomi Shemer had made a mistake in Hebrew, as he thought that the saltbush had no scent. However, this plant has a typical scent (ask every Bedouin in the desert), and Naomi Shemer knew it very well. I talked with her about it and she said that when she reaches the entrance road to her kibbutz, Kinneret, there is a special scent in the air. It derives from Atriplex halimus shrubs growing on a rare outcrop of the soft Lisan Formation rocks near the bridge. Her description, in a few words, is more accurate than any available GPS coordinates. Finding a new invading species of Atriplex in the N. Negev in November 2012 became a driving force for me to write about the Atriplex species.

Atriplex halimus
This plant grows in Israel and around the Mediterranean in a wealth of habitats that are difficult to connect. The distribution map (in the website Euro+Med Plantbase) shows that it grows all around the Mediterranean basin. Anyone who is used to seeing it in wadis in the desert will be surprised to see it on the Mediterranean beach. In Israel it inhabits beaches in the vicinity of ancient cities (e.g. Ashkelon, Ashdod, Caesarea and others). I came across it also in Crete, Greece, France and Spain and fully agreed with the chorotype designation “Mediterranean.” When I was 15 years old I joined Prof. Naftali Tadmor (Kofish), my biology teacher’s husband, to inspect his experimental plots in re-seeding pasture plants in the large wadis around Sde Boqer. A. halimus became good fodder for sheep and goats raised in that kibbutz in the 1950s. The experts in re-seeding pasture plants in the Ministry of Agriculture planted it and its relatives in the experimental station of Migda, near Gilat, in the N. Negev.
During my military service, dealing with “Field Education,” I searched for the saltbush everywhere. It assured my ability to give a lesson on edible plants. Its leaves are edible and it is already mentioned in the Bible (Job 30, 4) in “who cut up saltbush by the bushes”… relating to poor people eating it. In the cooking lesson I liked to have a group of soldiers pick A. halimus leaves from the stem and add them to a pot of boiling water to make soup, adding a few cans from the battle-rations.

A. halimus, growing in wadis, was beginning to make sense of our attempts to understand the vegetation map of the Negev. As we progressed in mapping the vegetation outside wadis we took a small step forward in understanding the wadis’ vegetation. Saltbush shrubs grow plentifully in desert wadis that drain landscape units rich in chalk, marl, and clays; the soils developing on these rocks are saline. Such sites are present in the Judean Desert along the Jerusalem-Jericho road and the Yerocham – Sde Boqer road in the Negev.

Compared with these wadis, those draining hard limestone sites are less saline and support shrubs of Thymelaea hirsuta and Retama raetam as the dominants. During our studies of the vegetation in Sinai we drove many kilometers along the main wadis of Gebel Igma and saw huge quantities of A. halimus. Gebel Igma is made up entirely of chalk rocks.
During my half year stay in Montpellier, S. France, I saw A. halimus growing along the Mediterranean beach (e.g. Cote d’Azure) and in vegetation belts at the opening of the river Rhone (Bouches du Rhone). This habitat reminded me of outer belts in wet saline soils along the Mediterranean coast, the Jordan Valley, the Dead Sea -, and the Arava Valleys. In 1978 I spent a sabbatical year in California. Passing along the road in the center of the huge valley along the Californian mountains, I reached low hills dominated by Atriplex polycarpa. This was near Kettleman City, in San Joaquin Valley. The space between the Atriplex shrubs was covered with annuals. After the first rains I saw plant-less patches around that Atriplex shrubs in the grassland and in places where dead shrubs left their lignified roots. During that year I summed up my study on recycling of salts by salt-resistant (halophyte) shrubs in the Judean Desert.

The halophyte absorbs salty water from deep layers of the soil and returns the salts to the soil surface in the falling leaves. A PhD student of a friend of mine at Davis University in California, scattered seeds of Atriplex polycarpa in the grassland and did not succeed in getting even one seedling. I found plenty of A. polycarpa seedlings in the empty patches of recycled salt below the Atriplex plants. I saw this phenomenon in the circles of salt-induced soil in the Judean Desert. I could conclude that the halophytes constitute permanent positions for the halophyte germination and establishment.

In 1989 I studied with Yoram Yom-Tov the relationships between nests of harvesting ants and the vegetation developing above them, near Kochav HaYarden. The dominant plants of the herbaceous vegetation were Triticum dicoccoides, Hordeum spontaneum and Avena sterilis. A tall shrub of Atriplex was growing there and my first thought was that it was A. halimus. However, after studying the specimen in the herbarium I saw that it was more similar to the Australian Atriplex nummularia. I assumed that someone had grown A. nummularia on Ramot Yisaschar or the Esdraelon Plain, and a seed had germinated, producing one shrub surrounded by herbaceous vegetation. I considered the possibility that A. nummularia could be planted and escape from cultivation in additional places and added this species to the “Distribution Atlas”… (Danin 2004). When we started to prepare the second edition of Flora Palaestina, I took on the task of reviewing the Chenopodiaceae (Goosefoot Family). I intend to study the two shrubby species of Atriplex throughout the country.

Atriplex leucoclada
Atriplex leucoclada belongs to the original flora of Israel; its presence in the Middle East is not assisted by human activity. Its role in the natural vegetation is that of a colonizer in the desert and it occupies habitats disturbed by natural- and human induced processes. It may be an annual or a perennial. During our investigations in Sinai we reached Gebel el ‘Igma, which is a botanical garden or paradise for plants of the Goosefoot family. We arrived there after a rainy year following many drought years. Species known to have high longevity, such as Salsola tetrandra died there during the drought years. Near each dead shrub there was a pioneer plant of A. leucoclada that germinated and developed in the rainy year and died after one year; there were no competitors there. At higher elevations, where Artemisia sieberi replaced S. tetrandra, Atriplex leucoclada developed as they did near the Salsola shrubs. When we returned from one of the excursions to Sinai we passed Mizpe Ramon after the road northwards had been resurfaced. A green “garden” of Atriplex leucoclada had developed on the crushed rocks near the road. A few years later Artemisia sieberi and its regular companions returned to cover the soil near the road and the pioneer A. leucoclada disappeared. In crevices and soil pockets of large rock outcrops there are perennial plants of A. leucoclada with a lignified trunk. One may assume that these perennial plants function as a living seed-bank. This takes place when new habitats, with no competitors, develop naturally (following drought or a high rate of erosion in a large wadi's floor) or as a result of human activity. Atriplex leucoclada has a high rate of morphological variability. M. Zohary (1966) in Flora Palaestina, related to this species as having three varieties differing in their fruit morphology. In 1972, I arrived at the home of Paul Aellen (the world expert in this field), with a package of Atriplex specimens collected in Israel and Sinai. I showed him how one fruiting branch carried three varieties. He agreed with me that the variability does not justify recognition at the varietal level. We did not succeed in publishing our conclusion because he passed away.

Atriplex semibaccata, Atriplex suberecta and Atriplex muelleri
In Atriplex semibaccata, the leaves, their surface and the fruit shape before maturation, are similar to many other species of Atriplex. However, this species is unique in having a red, ripe, juicy fruit (Fig. 20.1.1). The female flower, as in the other species of Atriplex, has a pair of bracteoles with a typical long triangular tooth subtending the fruit (Fig. 20.1.2). The bracteoles are united almost to their tip and become juicy when ripe. It is reasonable to assume that the plant passed through evolutionary processes in which it adapted to being dispersed by small birds attracted to the juicy red diaspore. After being eaten, the fruit passes through the digestive system of the bird, unaffected, and is dispersed as part of its excrement. Ripe fruits, drying in herbarium specimens, become black. This seems to be the reason for a description of a variety with black fruits in literature. A. semibaccata grows in great quantities in dry parts of the country, e.g. Be'er Sheva, in sites disturbed by man. Most figures of this plant were photographed in the industrial park of Omer, where soil was removed in order to form parking lots. A. semibaccata is treated in scientific literature as an annual; however, in areas where disturbance ceased, it may become perennial. The light grayish color of the leaves derives from vesicular hairs covering the leaf (the white dots on leaves in Fig. 20.1.1). In winter, while being full of salty fluid, the vesicles are transparent and allow solar radiation to penetrate easily. In the dry season, when the hairs’ content dries up, they become white and reject radiation. A quantitative study of such vesicular hair of another species of Atriplex was carried out in Stanford, California.

Another species, of Australian origin, that encroached into disturbed habitats in the dry lands of the country, is Atriplex suberecta (Fig. 20.1.3). When M. Zohary edited the first part of Flora Palaestina (1966), there was no awareness of the penetration of the plant into the study area, hence the key in Zohary's book led the reader to Atriplex rosea (Fig. 20.1.4). They differ in the general morphology of the adult plant. A. rosea is an erect, whitish plant; its bracteoles are more than 3 mm long. A. suberecta is a recumbent plant with a dark green crown, and its bracteoles are 2-3 mm long. It grows in disturbed habitats in the moist part of the country as well. Atriplex muelleri is another recumbent species of this group of Australian invaders, confined to disturbed habitats of the Negev. It differs from them by having emaerginate leaves (Fig 20.1.5), attenuating to a short but clear petiole. The leaves and stems are densely covered with vesicular hairs and look more whitish than most of the plants around it. Its diaspores differ from the other species (Fig. 20.1.5), but there is no need to use them in differentiating them from the other species. During the 1960s it was a rare plant found here and there among the Atriplex suberecta plants. At present, Atriplex muelleri is the common one. It is interesting to note that a friend of mine, Dr. Filip Verloove, the keeper of the National Herbarium of Belgium, suspected that he had found this species in the Canary Islands. He asked for, and I sent him, material from the Beer Sheva area for comparison.

Fig. 20.1.1: Atriplex semibaccata. The white dots on the leaves are vesicular hairs which became dry upon aging.

Fig. 20.1.2: A single female flower. The pair of bracts subtending the fruit became juicy and red towards full ripening.

Fig. 20.1.3: Atriplex suberecta – one of the Australian invaders.

Fig. 20.1.4: Atriplex rosea – a local species (not invader) that abounds at roadsides and human-disturbed sites in the Mediterranean territory. The white cover is dried-up vesicular hairs.

Fig. 20.1.5: Atriplex muellerii, an Australian annual invader, out-competing many local plants in human-disturbed land. May be recognized by its emarginate leaves and a general white-gray color.