Physiognomy and Structure: Even-aged Pinus clausa stands can be up to 25 m tall, with an open or closed canopy. The more open scrub vegetation is characterized by having a fairly open pine canopy averaging approximately 7 m in height. Beneath the Pinus clausa, Quercus spp. and other species form a dense to open layer of shrubs and stunted trees. This alliance includes coastal examples with an open Pinus clausa canopy which are generally referred to as "coastal scrub" as well as inland Florida Peninsula ridge examples called "Florida scrub."

Floristics: This alliance includes both coastal and interior scrub vegetation, usually with a sparse canopy of Pinus clausa over dense to open scrub Quercus spp. and other smaller shrubs. Beneath the Pinus clausa, Quercus spp. and other species form a dense to open layer of shrubs and stunted trees. Typical woody species include Quercus geminata, Quercus myrtifolia, Quercus chapmanii, Serenoa repens, Ceratiola ericoides, Chrysoma pauciflosculosa (Gulf Coast only), Lyonia ferruginea, Quercus inopina (southern peninsular Florida only), Sabal etonia (peninsular Florida only), as well as (Gulf Coast only) Conradina canescens and Clinopodium coccineum (= Calamintha coccinea). Sabal palmetto is common in the eastern portion of Gulf Coast scrub. Quercus laevis, Quercus virginiana, Quercus hemisphaerica, and Magnolia grandiflora are found in inland Pinus clausa forests in the Florida Panhandle. The understory/shrub layer usually consists of scattered clumps of Ceratiola ericoides and may be quite open. Other shrubs include Castanea pumila, Ilex opaca, Ilex vomitoria, Licania michauxii, Osmanthus americanus var. americanus, Serenoa repens, Vaccinium arboreum, Vaccinium stamineum, and Yucca flaccida. Some Gulf Coast examples contain Smilax pumila, with sparse herb layer which includes Croton argyranthemus, Dichanthelium commutatum, Eriogonum tomentosum, Euphorbia floridana, Pityopsis graminifolia, Polygonella macrophylla, Rhynchosia cytisoides, Rhynchospora megalocarpa, and Silphium compositum. A denser Pinus clausa and Quercus spp. closed canopy leads to a less dense ground cover. The ground layer frequently includes fruticose lichens such as Cladonia leporina and Cladonia evansii (= Cladina evansii), which may form close to 100% cover in some places.

Dynamics:  Florida scrub is pyrogenic with plants and animals adapted to fire. This vegetation is maintained by high-intensity, infrequent fires or by coastal processes near shorelines. Litter-fall rates are high, while turnover rates are low, contributing to fuel buildup (Lugo and Zucca 1983). However, scrub typically lacks fine-textured fuels necessary to ignite fires; most scrub fires ignite in other adjacent vegetation. If fire spreads into scrub it is only under severe conditions of high wind, low humidity, and low fuel moisture. When fires occur in scrub they are often stand-replacing events. Pinus clausa, if present, is killed outright but may regenerate from seed released from serotinous cones. The Pinus clausa in the Florida Panhandle and southern Alabama has a low proportion of serotinous cones. By contrast, the Pinus clausa on the Lake Wales Ridge in central Florida mainly has serotinous cones, which open after high-intensity wildfire and regenerate even-aged stands. The shrub layer is typically killed back to ground layer but rapidly resprouts and returns to prefire levels of cover (Abrahamson 1984). Other species such as Ceratiola ericoides may regenerate from seeds stored in soil (Johnson 1982). Several narrowly endemic herb species exhibit peaks in survival, recruitment, and density after fire (Menges 1999). Many scrub fires burn heterogeneously with resulting patches of unburned fuels, especially in the most xeric types like rosemary scrub (Menges 1994). In the sustained absence of fire, smaller shrubs and herbs may be lost as a consequence of increasing dominance of Quercus spp. stems (Menges et al. 1993).

This system has likely persisted on ancient dunes since the Pleistocene (Laessle 1968), but remaining examples are merely remnants of vegetation which was expansive in the late Pleistocene (Myers 1990). The stature and appearance of Florida scrub may be due primarily to nutrient-poor soils, to which many of the scrub species have adapted evergreen habits (Monk 1966). Drought stress is most likely during winter and early spring, but frequent fog during these periods may ameliorate such conditions (Menges 1994). Surprisingly, given the excessively well-drained soils, drought stress may not be an important ecological factor except to limit seedling establishment (Myers 1990). More research is needed on the dynamics of this community.