Eleocharis divaricata
Eleocharis divaricata Keskin
Some Observational Notes
* PDF of this blog with a gallery of photos showing characteristics : archive.org or academia.edu
Location
Eleocharis divaricata is located in the western part of Antalya city on the Boğa Çayı in the natural seasonal part of the waterway, immediately north of the Boğa Çayı Park - that is, north of the wall that was built in 2019 across the Çayı (just north of the major roadway) to create an artificial reservoir of deep water to its south for the Park (see satellite photos at end). The species is not known from any other location.
Range Currently
The plant's presence stretches about 800 metres northward from that wall, along the east side of the river, beyond which I didn't spot any examples when I last looked, though there may be some. The west side I explored on 2025-01-08 and did not spot any but should be investigated again.
River Flow
The river is generally low much of the year, but it swells in the winter wet season, a little way onto the flats on its sides, and presumably rises under the surface further to the sides where no flow is visible to the eye.
These rainfalls seem to have occurred later in recent years. On Google Earth, you can examine satellite images back to 2005 with an additional one from 1985, which show that the river levels have fallen substantially particularly in the recent decade, which agrees with a friend who noted the reduction in summertime river levels in the last decades, and that where rivers used to have a visible trickle all year round that flow is now not seen, although presumably again there may be some flow under the surface. In addition, it is clear from the historic satellite views that the river only spreads slightly onto the side flats, suggesting in centuries past, when the plant was growing, it perhaps flowed far more strongly than it does today.
It should be added that people are also taking more water for irrigation year by year whose importance would need consideration for the long dry season today.
The falling river flow no doubt reflects lessening rainfall. Although changes in rainfall are to be expected due to climate change, there are also natural multi-decadal cycles to the climate, so rainfall is perhaps not going to remain constant under any scenario and may possibly strengthen again at some point.
Range in the Past
Judging from the historic satellite views, the Boğa Çayı Park was built from 2018 over a habitat similar to where the plant is now found, so presumably the creation of the Boğa Çayı Park eradicated 600 m of the plant's territory, and it is quite plausible that this final river outlet lost to the Park was or would now be the plant's main base territory, and that what now remains of the plant may or would be the outlying area that trailing northward from that.
Furthermore, the historic satellite views suggest some areas a little further upstream might have been suitable for it until about 2016, which appear now to have dried up with the falling river flow.
Changing River Course
It is also noticeable on the satellite views that the river changed its course in 2008 or 2009 in the flats there. It is hard to know how the plant kept up with such an alteration, although it could be that it simply repopulated from an area unaffected by the change, however with its territory now presumably halved by the creation of the Park and the river seemingly drying up it would seem much more vulnerable to another such change of river course should it occur again after a strong rainfall.
Habitat Particulars
The ground where the species grows is alongside the river edge when risen, and is damp and fine-gritty and inhabited by small damp-loving plants such as Veronica beccabunga and Fimbristylis bisumbellata, and when samples were taken, the ground under the surface where it was growing was black (see end photos).
Encroaching Vegetation
One further kind of threat not already mentioned is that of large vegetation such as Arundo donax that seems to find its way everywhere and which already grows very nearby in swathes alongside the waters.
Visual Appearance
Visually, the plant clusters resemble hedgehogs, forming low domes of short rather straight-looking stems (mostly about 5 cm) topped with sizeable Eleocharis heads. These domes are fairly consistent in size, reaching 10-20 cm across, though you sometimes have two that run into each other and merge at the edges. As such, the plant does not resemble any other Turkish Eleocharis in general appearance - the stems are not thread-like, nor upright, but point in all directions.
The nutlets mature black not brown (though they appear brown when not fully mature), about 1 mm long.
As well as the usual nutlets from pollination, it unusually also appears to produce ground-level cloning-fruits that do not require pollination, and those encourage horizontal spread as well as the more distant dispersal of the normal nutlets.
Flowers and fruits were seen on it between late Oct to early Dec and therefore November is a good visiting date. No doubt the season stretches beyond that range.
Anyone looking to find the plant, particularly outside flowering time, should familiarise themselves with the appearance of some other superficially similar plants growing in the same location that are (or may happen to be) small: Fimbristylis bisumbellata, Cyperus fuscus, Pycreus flavescens, Scirpoides holoschoenus, Fimbristylis ferruginea subsp. sieberiana (nearby), Juncus articulatus, Juncus fontanesii subsp. pyramidatus.
Summary
In summary, this seems to be a very vulnerable species. It will be important to keep a close eye on it in terms of encroaching vegetation and changing hydration, and to make periodic counts of its numbers. In 2023 I took photos of 13 large clumps from the eastern area stretching not far from the wall mentioned.
I would not expect there to be imminent plans to expand the Park further, and being a major waterway with sudden large winter rainfalls the river cannot be fundamentally blocked. However it cannot truly be considered secure from human threats. The general area does have active developments, and people drive about on the gravel flats beside the river, although a small degree of the latter disturbances can in fact assist a small short-lived plant to spread and compete against inroads of tougher longer-lived larger plants.
As with all extremely vulnerable species, the question of whether a second home in a similar habitat beside a river or reservoir could be made for it should always be considered.
Research Questions
● What are the plants like throughout the year?
● How long do they live?
● How big are the ground-level nutlets and how far do they spread?
● What is the longevity of the two types of nutlets under different conditions?
● What is the plants' spread on the west side of the river?
● Recheck the distance of spread along the east side.
● What is the hydration under the ground at different distances from the river in different seasons?
● How long can the plants survive partially or fully submerged?
● Do a plant count as baseline to compare future counts against.
● Can historical rainfall and sunshine records be acquired?
Botanical Description
The species was published in 2021 and a PDF can be found for download at either of:
● https://dergipark.org.tr/tr/download/article-file/1456072
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