This consists of a dense, almost impenetrable mass of small trees and shrubs together with creeping and climbing plants, which can be between 3 and 5 metres high. The bulk of the Upper Rock comprises this type of vegetation. The main trees/shrubs found here are: Rhamnus alaternus (Mediterranean Buckthorn); Osyris quadripartita (Osyris); Olea europaea (Olive); Pistacia lentiscus (Lentisc); Pistacia terebinthus (Turpentine Tree); Bupleurum fruticosum (Shrubby Hare's Ear); Smilax aspera (Rough Smilax); Clematis cirrhosa (Virgin's Bower); Aristolochia baetica (Pipe Vine); Asparagus album (White Asparagus); Lonicera implexa (Honeysuckle); Ruscus hypophyllum (Southern Butchers Broom); Coronilla valentina glauca (Shrubby Scorpion Vetch); Calicotome villosa (Spiny Broom); Teucrium fruticans (Tree Germander); Laurus nobilis (Sweet Bay, Laurel); Celtis australis (Nettle Tree); Ceratonia siliqua (Carob); Chamaerops humilis (Dwarf Fan Palm); Ephedra fragilis (Joint-Pine); Jasminum fruticans (Wild Jasmine); Prasium majus (Prasium).
This consists of fairly open vegetation formed by low shrubs, between knee and waist high. This type of vegetation is not extensive locally, and is generally found in the southern parts of the Rock, e.g. around Martin's Path, Levant Battery, Hole-in-the-wall, etc. The more open nature of this type of vegetation enables the growth of a greater variety of species than is possible in the more overgrown maquis.
Many of the shrubs found in the maquis are also found here, but of a lower stature. Many of the shrubs are aromatic, such as Teucrium lusitanicum (Felty Germander); Rosmarinus officinalis (Rosemary); Ruta angustifolia (Narrow-leaved Fringed Rue); Sideritis arborescens (Shrubby Sideritis); Lavandula dentata (Toothed Lavender); Lavandula multifida (Cut-leaved Lavender). Here we also find Euphorbia squamigera (Warty Spurge); Stipa tenacissima (Esparto Grass); Teline linifolia (Teline); and Chamaerops humilis (Dwarf Fan Palm). In a small area along Mediterranean Road we also find Cistus albidus (Grey-leaved Cistus) and Cistus Salvifolius (Sage-leaved Cistus). This is rather surprising since these are plants of acid soil. It must mean that this restricted area is more acid than the surroundings. Bulbous plants abound, e.g. Scilla peruviana (Giant Squill); Urginea maritima (Sea Squill); Allium ampeloprasum (Great Round-headed Leek); Gladiolus communes (Common Gladiolus); Asphodelus aestivus (Common Asphodel); Asphodelus albus (White Asphodel), and a proliferation of other herbaceous plants which provide an explosion of colour during the Spring months (March to May).
The formidable limestone cliffs which form the North Face of the Rock and the East side, the rocky upper ridge and the outcrops and roadsides within the maquis, provide a habitat where can be found a large number of interesting and unique species. Here we find Silene tomentosa (Gibraltar Campion), a very rare plant found nowhere else in the world. This plant was believed extinct until rediscovered in 1994. Other plants are Iberis gibraltarica (Gibraltar Candytuft), a plant of North Africa and found nowhere else in Europe except Gibraltar; Cerastium gibraltaricum (Gibraltar Chickweed) also unique to Gibraltar, Saxifraga globulifera var. gibraltarica (Gibraltar Saxifrage), a variety unique to Gibraltar; Thymus willdenowii (Gibraltar Thyme), very common locally and very rarely, if at all, found elsewhere. Apart from these special species we find Iris filifolia (Narrow-leaved Purple Iris); Dianthus caryophyllus (Clove Pink); Scilla peruviana (Giant Squill); Narcissus papyraceus (Paper-white narcissus) which grows in huge quantities between the months of November and January; Colchicum lusitanum (Southern Colchicum); Lobularia maritima (Sweet Alison); Antirrhinum majus (Snapdragon) which is also found on walls and rooftops in the town area; Gladiolus communes (Common Gladiolus); Euphorbia characias (Large Mediterranean Spurge); Aeonium arboreum (Tree Houseleek), and many others. The general appearance in Spring is that of a giant rock garden run wild. It is in this habitat that one can find any of the ten species of wild orchids found on the Rock. These are very rare and difficult to find. The ones found in Gibraltar are Ophrys apifera (Bee Orchid); Ophrys fusca (Brown Bee Orchid); Ophrys lutea (Yellow Bee Orchid); Ophrys tenthredinifera (Sawfly Orchid); Ophrys bombyliflora (Bumblebee Orchid); Ophrys speculum (Mirror Orchid); Gennaria diphylla (Two-leaved Gennaria); Serapias parviflora (Small-flowered Tongue Orchid); Spiranthes spiralis (Autumn Ladies Tresses Orchid); Anacamptis pyramidalis (Pyramidal Orchid).
Sea cliffs and shoreline
This seemingly inhospitable environment, whipped by the Easterlies and South-Westerlies, and lashed by sea spray, provides the ideal habitat for certain plants which are only found close to the sea. These include Limonium emarginatum (Gibraltar Sea Lavender), a plant which is believed to be a North African species, and very rarely found elsewhere in Europe. Other species found here are Crithmum maritimum (Rock Samphire); Suaeda vera (Shrubby Seablite); Limonium sinuatum (Winged Sea Lavender); Asteriscus maritimum (Sea Daisy), actually found throughout the Rock; Frankenia laevis (Sea heath); Senecio bicolor cineraria (Cineraria). Here we also find the very rare Senecio leucanthemifolius (Coastal Ragwort), and Mesembrianthemum crystallinum (Ice Plant).
Great Eastern Sand Slopes
These are prehistoric consolidated sand dunes, created by wind-blown sands during a time when sea levels were much lower than at present, and sandy plains spread eastward from Gibraltar. This sandy soil provides a unique habitat not only for plants of sandy shores, but for many others. The plants that can survive in this habitat are adapted to withstand salt-laden winds, high temperatures with no cover from the sun, and scarcity of water. Here we find Ononis natrix ramosissima var. gibraltarica (Gibraltar Restharrow), a variety which is unique to Gibraltar. We also find Eryngium maritimum (Sea Holly); Linaria pedunculata (Branched Toadflax); Daucus carota (Wild Carrot); Cyperus capitatus (Sand Sedge); Silene nicaeensis (Sticky Catchfly); Silene littorea (Shore Campion); Medicago marina (Sea Medick); Pancratium maritimum (Sea Holly); Dipcadi serotinum (Brown Bluebell); Euphorbia baelica (Southern Spurge); Cachrys libanotis (Sand Cachrys); Cakile maritima (Sea Rocket); Allium sphaerocephalon (Round-headed Leek); Crucianella maritima (Coastal Crucianella); Delphinium nanum (Violet Larkspur); Dianthus broteri (Fringed Pink); Glaucium flavum (Yellow Horned Poppy); Lotus creticus (Southern Birdsfoot Trefoil); Malcolmia littorea (Silver Sea Stock); Verbascum giganteum (Giant Mullein). A number of these species are also found in North Front Cemetery which is all that is left of the sandy isthmus which separated the Rock from mainland Spain.
At Windmill Hill Flats we find a rather hostile environment: a flat, wind-lashed terrain, with thin, poor stony soil. Despite all this, Windmill Hill is a treasure-house of plant species. In Spring it is a riot of colour, albeit for a brief period. Here we find a number of species which are not found elsewhere on the Rock, including Crocus serotinus salzmannii (Southern Autumn Crocus); Salvia verbenaca (Wild Clary); Echium parviflorum (Small-flowered Bugloss); Plantago serraria (Saw-toothed Plantain); Hedysarum coronarium (Italian Sainfoin); Mantisalca salmantica; Minuartia geniculata (Pink Sandwort); Tetragonolobus purpureus (Winged Asparagus Pea); Lathyrus annuus (Annual Yellow Vetchling). Other important plants found here better than anywhere else on the Rock are Ornithogalum orthophyllum (Star of Bethlehem); Romulea clusiana (Romulea); Gynandriris sisyrinchium (Barbary Nut); Borago officinalis (Borage); Ecballium elaterium (Squirting Cucumber); Echium plantagineum (Purple Viper's Bugloss).