1. Delineation of the floristic regions of Greece
Internal distribution data are coded using the 13 floristic regions of Greece (Fig. 1), as defined for the Flora Hellenica project (Strid & Tan 1997). Borders between the 13 floristic regions are self-evident in most cases, but for the following mainland regions specification is needed:
- Border between StE and SPi: A line between the following points: 38.53/21.10 – 38.54/21.20 – 38.56/21.30 – 38.59/21.38 – 38.59/21.50 – 39.00/22.03 – 39.05/22.19.
- Border between SPi and NPi: A line between the following points: 39.37/20.11 – 39.38/20.30 – 39.39/20.41 – 39.40/20.58 – 39.46/21.06 – 39.44/21.14 – 39.44/21.21 – 39.43/21.26 – 39.44/21.30 – 39.47/21.45. The border between SPi and NPi in the Metsovo-Ioannina area has been drawn just S of the old national road so that the Katara Pass, the town of Metsovo and the meadows just N of Metsovo are all in NPi. It more or less coincides with the border between an area of limestone in the south and serpentine in the north.
- Border between NPi and NC in the Kastoria area follows an almost straight line from 40.21/21.18 to the Albanian border at 40.34/21.03, which places it c. 5 km SW of the town of Argos Orestikou.
- Border between StE - Spi - NPi and EC - NC: a line between the following points: 38.53/22.33 – 38.55/22.28 – 39.05/22.19 – 39.18/22.10 – 39.33/21.55 – 39.47/21.45 – 40.00/21.36 – 40.14/21.25 – 40.34/21.02.
- Border between EC and NC: A line between the following points: 39.33/21.55 – 39.42/22.13 and then along the Pinios River to the sea at 39.54/22.43.
- Border between NC and NE: Along the Axios River from the Bulgarian border to the sea.
Fig. 1. The floristic regions of Greece (Strid & Tan 1997).
2. System for the chorological categories
The chorological category/type of a taxon is defined by its current area of native distribution and refers to a group of taxa with largely coinciding distribution. In the local and regional floristic investigations conducted during the last decades in Greece, the researchers allocated chorological types to plant taxa, applying the systems established by Pignatti (1982) for the Italian flora and by Oberdorfer (1994) for the central and north European floras.
The “Greece-centered” system of chorological categories/types is established here to better reflect and circumscribe the distribution ranges of the taxa of the Greek vascular flora, given that Greece is a country of Southern Europe, of the Balkan Peninsula and of the Mediterranean basin. Based on this new system, the Greek vascular flora can be assigned to twenty one (21) chorological categories distinguished for native taxa, and to one (1) group of various chorological categories representing different origins of alien taxa. Definition of the chorological category of each plant taxon is chiefly derived from the following basic phytogeographical sources: Tutin & al. (1968 -1980, 1993), Strid (1986), Strid & Tan (1991, 1997, 2002), Davis (1965-1988), Czerepanov (1995), Hultén & Fries (1986), Euro+Med PlantBase (2006-), in addition from recent taxonomic publications related to various taxa at specific and subspecific level.
Descriptors and abbreviations for each of the 22 chorological categories (for the native and the alien taxa of the Greek vascular flora) as adopted and used in the checklist are given in the table below.
3. Life-form categories
The life-form categories for the terrestrial and the aquatic (hydrophytes) vascular plants of the Greek flora are coded according to the life-form system of Raunkiaer (1934) which is based on a functional criterion – the position of the perennating meristem (buds) during the unfavourable season; subsequent extensions to Raunkiaer’s system by Ellenberg & Mueller-Dombois (1967) have also been taken into consideration.
Descriptors and abbreviations for each life-form category as adopted and used in the checklist are given in the table below.
4. Habitat categories
Eight groups (categories) of habitat types are distinguished. Descriptors for each category and abbreviations as used in the checklist and the Flora of Greece website are given in the table below.
The range of habitats that a species occupies falls mostly into one habitat category but may comprise two or more categories. Generally a category is given only when it corresponds to a considerable proportion of the populations of the respective species. If more than one category applies the two or more abbreviations are in alphabetical order. The order of habitat symbols does not express prevalence. If one out of two or more habitat categories clearly prevails – i.e. representing at least about two thirds of all known populations – the respective habitat abbreviation is underlined.
We tried to keep overlap between the categories to a minimum. However, the following cases may deserve further explanation. Cliff-dwelling high-mountain species are exclusively H, and C H only if found additionally in mountain cliffs or ravines below the timberline. Species of coastal disturbed habitats are listed only under M, unless occurring also in ruderal habitats farther inland, in which case M R is assigned. A species of coastal wetlands is listed under M and not A M unless it occurs also at inland wetlands. Aquatic field weeds, such as those of rice fields, are assigned R while other species of more or less disturbed aquatic habitats are assigned A R or A. Species of the habitat category R need not necessarily be restricted to human-made habitats. Species of naturally nutrient-rich habitats and disturbed pioneer sites such as in rock shelters, on talus and in dry streams also belong here.
It should be noted that the degree of uncertainty in allocating habitats to plant taxa in Greece is high in many cases, even with only eight coarse categories adopted. Many species have been seen in the wild by few persons, and some by one or no living person. For many taxa, hardly any useful, or no, ecological or habitat statements are available in literature. Only a fraction of the Greek flora occurs in published phytosociological records. Habitat descriptions in taxonomic studies or on herbarium specimen labels are often short or misleading, or comprehensive works attempt to enumerate all possible habitat conditions under which a species might be encountered. In any of these cases the allocation to a predominant habitat category is made difficult. Therefore, many habitat assignments were made on the basis of records from outside Greece. Such cases might represent deviations to the ecological preferences of Greek populations. Nevertheless, as the degree of uncertainty is difficult to assess – it may be high or low – we refrained from adding a symbol to emphasize uncertainty.
5. Range-Restricted taxa
As Range Restricted (symbol: r) are characterized those taxa that occupy a limited area of distribution not exceeding a distance of 500 km or, in other words, their most distant known populations expand along a linear distance of 500 km or less. The estimation of linear distance is easily provided today by Google Earth and its tools. This distance is not affected by topography, altitude, habitats, bodies of fresh or sea water, or political borders. Thus, the Ionian and the Aegean Seas, for example, can contribute to the linear distance of taxa distributed from the western to the eastern parts of Greece. In opposite to the endemic taxa, the Range Restricted taxa may well be shared by two, three or more countries.
Although most endemic Greek species fall within the Range Restricted category, this is not the case with all endemic taxa. The N-W Greek axis (from Gavdos Island to north Thrace) measures c. 785 km and the NW-SE axis (from the island of Othoni to the island of Strongili) measures c. 990 km. Therefore, endemic species found in many territories or phytogeographic regions of Greece may not be Range Restricted. For example, the endemic Ebenus sibthorpii is distributed from Rodos Island in the south up to Thessaly in the north, spans a distance of 560 km, and is not a Range Restricted species.
The assignment of any Greek taxon to the Range Restricted category requires a good knowledge of its overall distribution. Cosmopolitan, European or widely distributed Mediterranean species are automatically excluded from the Range Restricted category. As a rule, taxa growing in Crete and any other Balkan countries are not Range Restricted. European Turkey is included in this rule, Anatolia is excluded. Taxa distributed in Greece, Turkey and any of Montenegro, Croatia or Bosnia & Herzegovina are not Range Restricted. Many species distributed in the central Balkan area (i.e. northern Greece, Bulgaria, Albania, FYROM, Montenegro, southern Serbia, southern parts of Bosnia & Herzegovina and Croatia) belong to the Range Restricted category. Such taxa often contribute less to the importance of floristic diversity of any given Balkan country, compared to national endemic taxa, simply because they cross country boundaries.
The search for the most distant populations in Range Restricted candidate taxa involves a variety of floristic or monographic sources. The recovered information is either provided by the form of distribution maps (sometimes limited to administrative or phytogeographic divisions only and thus not detailed) or in geographic localities within a taxon’s distribution. The floras of the Balkan countries and Turkey are most important for making decisions on Range Restricted, followed by the floras of Italy, Cyprus and Libya. In marginal cases, i.e. when known populations expand to a distance of nearly 500 km, the R category is usually not applied since, as a rule, a species’ distribution is more possible to expand as a result of field work in the future than to contract.
The symbol ?r usually indicates uncertainty with respect to the exact distribution range of an entity that may belong to the Range Restricted category. The most common reasons of uncertainty are the following: i) the distribution of a species or subspecies within certain phytogeographic regions of Greece is currently being questioned, disputed or in need of recent confirmation, ii) the taxonomic entity is not recognized in the floras of neighboring countries, or its presence in a country is dubious, or a collective taxon’s name is used instead, iii) the entity’s range of distribution in a country other than Greece is critical but not precisely known, and iv) some old or local literature could not be accessed.
The Range Restricted list of taxa, in parallel to the list of endemics, is not a static but rather a dynamic list over the time. A better knowledge of a species distribution or the discovery of new populations may necessitate changes and transfers. By being independent from country frontiers and defined only by distance, the Range Restricted taxa may be useful markers in future works.
6. Native and non-Native (Alien) taxa
The criteria for considering a listed taxon as native are taken from Med-Checklist (see, e.g., Greuter & Raab- Straube 2008: xi). Native plants are presumed to have been present in what is today Greece, in the wild, before the end of the 15th century. This means that archaeophytes are considered as part of the native flora.
Non-native taxa, including cultigens that occur in at least one floristic region of Greece are termed aliens (xenophytes), and are included in the floristic catalogue provided that they are permanently established somewhere in the country. This may be true on a very local scale, and this may be cross-referenced by the relative explanatory note. Alien taxa considered as only casual, ephemeral introductions or occasional escapes from cultivation are excluded from the Floristic catalogue and the “Flora of Greece” website.