Other abundant plants in the open forests and savannas are Compositæ (Zemenia, Pectis, Spilanthes); Rubiaceæ (Spermacoce); Polygalaceæ; Iridaceæ; Moraceæ (Maclura, Ficus); Melastomaceæ (Miconia, Clidemia, Conostegia, Leandra); Cyperaceæ; Convolvulaceæ; Euphorbiaceæ; Bombacaceæ; Sauvagesia. Further, Myrtaceæ (Psidium, Alibertia edulis); Curatella americana (chamico); Roupala (danto hedliondo); Byrsonima crassifolia (nance); Miconia argentea DC. (santa maria); guacimo macho (Luhea), guacimo de ternero (Guazuma ulmifolia); burio (Bombax apeiba); ñambar (Cocobola); Davilla lucida; Duranta Plumieri; Proteaceæ; and Acacia scleroxyla Lonchocarpus atropurpureus, Dalbergia and many other Leguminosæ, especially Mimosa pudica, which gives large tracts in many places a special character, and still more so as, being often very abundant and the plants tangled together, a general movement all around is caused when one is touched.
Among the epiphytes and parasites may be mentioned small ferns, Peperomia, Epidendrum, Loranthus, Aroideæ, Tillandsia and other Bromeliaceæ, mosses, lichens, etc.
Professor Pittier attributes to this flora of the Pacific slope a more northern origin.
During the dry season the vegetation of the savannas almost disappears, the greater part of the trees and bushes shed their leaves and herbs become dry and brittle. Only along the rivers is some freshness observable. Toward the border of Nicaragua cacti appear, mostly species of Cereus, Opuntia, Phypsalis and Mammilaria. Professor Pittier also mentions an oak forest of Quercus citrifolia between Liberia and the Rio de los Ahogados, at a height of about one hundred meters above the sea. The peninsula of Nicoya is noted for a large lumber industry among its different cedars (Cedro dulce, C. amargo, C. real, etc.), mora and other trees. Towards the upper limits of the Atlantic tropical forests, below the oak region, Chamædorea, Geonoma, Bactris, Euterpe longepetiolata and other palms of the same groups, as well as Gulielma utilis (the pijivalle palm) and Carludovica microphylla are seen in great abundance, mixed with tree ferns like Alsophylla pruinata, Hemitelia horrida, Hemitelia grandifolia, etc. Higher up appears the region of oaks, principally Quercus retusa, Quercus granulata, Quercus citrifolia and Quercus costaricensis, with Buddleia alpina, Rubus, Lupinus, etc. Here is also the region of the common potato. This oak region slopes gradually down from east to west. The vegetation on the summits of the high mountains of Costa Rica is of a marked subalpine character, having a great number of northern genera, as Vaccinium, Pernettya, Alchemilla, Cardamine, Calceolaria, Spiræa, etc.
Certain types of vegetation are often more due to the sterile nature of the soil than to elevation.
Although a northern flora is frequent on the high terraces of San José and Cartago, that character is not general because of the introduction of cultivated tropical and other plants peculiar to Costa Rica.
On the southern high mountains two species of Podocarpus (P. taxifolia and P. salicifolia), one of Alnus (Alnus Mirbelii Spach.) and one of Weinmannia occur quite generally among the oak forests. Other distinct floral groups are represented by the vegetation along roads and fences, on potreros, in cultivated regions and along river shores. The latter especially are rich in herbaceous plants, grasses, bushes and woods of Bignoniaceæ, Myrtaceæ, Euphorbiaceæ, Mimoseæ, etc.
The potreros are characterized by Tagetes, Sida, Hyptis, olanum, Salvia, Mimosa pudica and M. sensitiva, etc. Along fences there grow nearly everywhere Erythrina corallodendron, Yucca aloifolia, Bromelia pinguin, Agave americana, Cereus, Spondias, Bursera, Cestrum, etc.
Prominent characteristic plants, besides the already mentioned species and genera, are the Piperaceæ and Melastomaceæ; further, species of Iriartea, Bactris and Raphia of the palm order, and Alsophylla, Schizæa occidentalis and Pteris aquilina of the ferns; still further Castilloa costaricana, Gunnera insignis, Ochroma lagopus, Gliciridia, Inga edulis, Chusquea maurofernandeziana, Erythrina corallodendron, Drymis Winterii Forst., Acacia Farnesiana, etc.
The passage from one flora to another is one of insensible gradations. Cultivated lands, as already stated, do not show any longer the original vegetation.