Note:  Some plants are categorized in more than one of the following habits as appropriate to their characteristics.


Agave-like plant

Perennial monocot plants with long, narrow, often rigid and "bayonet-like" leaves, these succulent or hard and durable, long-lived, often spine-tipped and sometimes with spiny margins, produced as a rosette or terminal cluster.  "Agave-like" species grow mostly in arid regions and now are mostly placed in genera of the Agavaceae and Liliaceae(Agave, ManfredaHesperaloe, Yucca, NolinaDasylirion in North America).  In this category are species with characteristically tall trunks (e.g., Yucca brevifolia) as well as those without trunks or with trunks of variable length (e.g., Agave lechuguilla).  Agave-like species with a distinctive trunk-like portion are here also categorized as trees.


Bamboo or cane

Perennial grasses with woody, usually hollow stems (culms) with conspicuously ringed nodes, usually clonal from a system of rhizomes and producing many tall, erect stems from the base.  Technically, bamboos comprise subfamily Bambusioideae of the grass family (Poaceae) and in our flora include ArthrostylidiumArundinariaBambusaChusquea,PhragmitesPhyllostachysPseudosasaSasa, and Schizostachyum.  Other tall, woody-culmed grasses in our flora, referred to as "canes" or "reeds," are similar in habit to bamboos but have developed independently in various groups of the family: Arundo andPhragmites (Arundinoideae) and Lasiacis and Saccharum (Panicoideae).  Bamboos and canes are primarily subtropical or tropical in their native distribution.


Cycad or palm-like plant

Cycads, palms, and other similar perennial plants with terminal clusters of large, strong, and durable leaves, often to 1 meter or more wide, usually palmately or pinnately divided into long segments at the end of a long petiole.  Palms and cycads are mostly tropical or subtropical.  In this category are included species with characteristically tall trunks (e.g.,Cocos nucifera) as well as those without trunks or with trunks of variable length (e.g., Sabal minor and Zamia pumila).  Palm-like species with a distinctive trunk-like portion are here also categorized as trees.



Herbaceous plants most commonly with relatively broad, usually pinnately veined leaves (contrasted with parallel-veined in "grass or grass-like" plants), with all perennating or overwintering organs at or below ground level.  The forb category, which was originally established in an agricultural context to contrast with grass and grass-like plants, includes a wide range of herbaceous growth habits, especially if aquatic plants are added.  Vining, creeping, and  trailing herbs also are included within this broad category (in the BONAP system).  Plants with annual stems becoming woody at the base are included as forbs. Primarily herbaceous plants bearing terminal buds at the tips of woody caudex branches at or near ground level are referred to the forb category; "cushion plants" belong with these.  However, members of the genus Rubus, which is weakly woody, have been scoredbroadly as shrubs and subshrubs, and are sometimes characterized as "succulent shrubs."


Grass or grass-like (graminoid) plant

Herbaceous plants with long, narrow, entire, parallel-veined leaves, often produced in a basal cluster, with all perennating or overwintering organs below the ground.  The flowers of these plants usually are reduced in complexity and thus inconspicuous.  Grasses and grass-like plants include all members of the monocot families CyperaceaeJuncaceae,Juncaginaceae, and Poaceae, some members of the Liliaceae, and all members of the pteridophyte family Isoetaceae, but similar leaved-species occurring in numerous dicotfamilies were not scored.  Bamboos and canes, which are woody and often have above-ground perennation, are included here but are also placed in a separate category.


Liana (woody vine)

Perennial plants with woody or lignescent above-ground stems that grow upward and into (or onto) trees and other vegetation or structures.  They bear overwintering buds and do not die back to a basal stem or rhizome in winter.  Lianas can often have weak, elongate, and flexible stems and gain support by twining, clambering, or climbing with tendrils, aerial rootlets, or other modified structures. 



Perennial plants with woody, above-ground stems that bear overwintering buds relatively evenly positioned on the stems and do not die back to a basal stem or rhizome in winter. Shrubs are multi-stemmed from the ground, generally attaining a low stature (variable in size but usually under 5 meters tall), and producing a poorly-defined crown.  Some shrubs may be creeping (e.g., Juniperus horizontalis, Gaultheria hispidula); others may be "mat-like" or "mound-like" (e.g., Arctostaphylos nevadensis).  Various exceptional species are also placed here (e.g., Coreopsis gigantea, a "fleshy-stemmed shrub";  Coreopsismaritima, a "hollow-stemmed shrub"; Leucanthemum nipponicum, a "soft shrub"), and some primarily shrubby species that occasionally reach tree size are also characterized as trees.  All mistletoes (Viscaceaeare scored as shrubs as well as parasites, following other precedents.  Members of the genus Musa, although herbaceous, are also scored as shrubs and subshrubs.



Perennial (rarely annual or biennial) plants with woody or lignescent above-ground stems but with overwintering buds only near the base of the plants, most of the stem dying back to near ground level each year and the upper part of the plant mostly herbaceous.  They are often termed "suffruticose" plants.  Subshrubs are usually multiple-stemmed from the base and of low stature, but some may attain 1-few meters in height.  The habit in some species that produce large plants grades into "shrubs" and the distinction between shrub and subshrub becomes arbitrary.  Species that might be categorized as subshrubs, however, show more variation than true shrubs in the degree of woodiness and overall size. Most of such habit intergradation occurs in western North America, where species of subshrubs are most numerous.  Intergrades between subshrubs and "forbs" also are common.  Some species produce tall, thick, and woody but annual stems (e.g., Sesbania spp., Helianthus spp., many Malvaceae), either completely by primary growth or sometimes with the addition of secondary wood.  These are placed here in both the forb and subshrub categories, but they are even characterized by some botanists as shrubs. All species of Rubus and Rosahave been scored as subshrubs.



Plants with stems and leaves very soft, fleshy, and often filled with juice or sap.



Perennial plants with woody, above-ground stems that bear overwintering buds and do not die back to a basal stem or rhizome in winter.  Trees usually have a single main stem, are at least 4 meters tall, and have a more or less distinct and elevated crown.  A few species produce normally short-lived but rapidly growing plants that occasionally attain tree-like proportions (e.g., Ricinus communis).  Likewise, members of the Musaceae treated within the Synthesis, although herbaceous, are scored as trees.



Perennial, biennial, or annual herbaceous, semi-woody, or woody plants with elongated, flexible stems supported above the ground via twining, sprawling, clambering, or climbing by tendrils or other modified organs over other plants or structures.  All herbaceous vines as here characterized are also scored as forbs.