Key to Genera and Families
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KEY TO GENERA AND FAMILIES Identification notes: The key is highly artificial and unabashedly pragmatic. One can get to the sub-keys (Key A, Key B, Key A7, etc.) by proceeding through the general key, or by jumping directly to the sub-key based on its “description”. In order to accommodate both access methods, some taxa are keyed in 2 or more sub-keys, but would logically be found only in one sub-key if one proceeded accurately through the general key. For instance, floating aquatic pteridophytes are keyed in both Key A2 and Key C1, though a logical procession through the general Key would key them into Key C1, and not allow them to appear as well in Key A2; they are keyed as well in Key A2, so that if it is apparent or determinable to the user that they are vascular cryptogams, they can be found via that key as well. The arrangement of leaves (alternate, whorled, or opposite) and their disposition (basal or cauline) is used frequently in the keys. Alternate leaves are attached at the stem 1 per node, opposite leaves 2 per node, and whorled leaves 3 or more per node. Note however, that alternate leaves are sometimes (especially at the base of plants or at the tips of woody branches, such as short shoots) arrayed with very short internodes, leading to them being closely clustered and mistakable as whorled or opposite. Note that some plants (Hypericum, Eupatorium, many Lamiaceae, many others) have a strong tendency to have axillary shoots in the axils of primary leaves; these are often referred to as axillary fascicles. “Axillary fascicles” tend to have smaller leaves (at least for a time) than the primary leaves, and to have short and compressed internodes; these should not be interpreted as whorled, and if and when they extend, will have the same leaf arrangement and size as the primary leaves. Leaf longevity is used in the keys, in regard to woody plants primarily. Evergreen plants are those that retain full leaf cover through the winter, while deciduous plants lose their leaves at the end of the growing season (for some species, sometimes well before autumn). Some plants are also described as tardily deciduous or semi-evergreen, meaning that they drop leaves gradually into the winter, so that they are sparsely bedecked with leaves or even bare by the initiation of new growth in the spring. Evergreen vs. deciduous (and semi-evergreen). {explanation}. Leaves of the previous season. Texture. Color. The basic growth form of the plant is used extensively in the keys. Woody plants have substantial secondary growth of wood, which makes their stems (in general) thicker, stronger, stiffer, and tougher. Woody plants are further subdivided into trees, shrubs, subshrubs, and lianas. Trees are generally more than 5 meters tall at maturity, and are often single stemmedHerbaceous plants lack substantial secondary growth of wood. Herbaceous plants are further subdivided into herbs and herbaceous vines. Shrub, tree, subshrub, herb, liana, vine. {complete explanation} Basal vs. basally disposed vs. cauline: explanation Lobes vs. teeth. {explanation} Learning families. Asteraceae, Euphorbiaceae, Cyperaceae, Poaceae, Lamiaceae, Apiaceae, etc. At various points throughout the key, a kind of shorthand is used in key leads to indicate the main evolutionary group involved: Lycophytes, Pteridophytes, Gymnosperms, Basal Angiosperms, Eudicots, and Monocots. While the readily visible characteristics of these groups have many exceptions, the following table will aid in their recognition (note that this table is pragmatically based only on the characteristics of those taxa in our flora). {check flower and plant sexuality terms and make consistent} {make oak fruit description and flower description consistent} Yellow: Things not in Virginia needing to be stripped out for FoV key Red: Additions and improvements needed for FoV and Regional Flora Hot Pink: Additions and improvements needed for the Regional Flora. Lycophytes Pteridophytes Gymnosperms Basal Eudicots Monocots Angiosperms Leaf size Very small (< 20 Very small scale Very small scale Small to large (> 3 Very small scale Very small scale mm long), or to very large leaves to very cm long) to large to giant leaves linear quill leaves large pinnately in Isoetes compound leaves Leaf Simple Usually Simple and scale- Simple (or Simple to Simple with few complexity complexly like or needle-like dichotomously complexly exceptions compound (1-5× (or 1-pinnately compound in compound (except palmately compound), but compound in Cabomba) or pedately also simple or Zamiaceae and compound in variously less Cycadaceae, and Arisaema and complicatedly fan-shaped and palmately or compound dichotomously pinnately veined in Ginkgo) compound in the giant leaves of Arecaceae) Leaf or Entire or Often toothed Entire or Entire Entire or Entire (rarely leaflet minutely toothed (diversely so), but minutely toothed variously toothed with spinulose toothing sometimes entire teeth in some aquatics) Leaf or Leaves not lobed Leaves and/or Leaves or leaflets Leaves not lobed Leaves and/or Leaves or leaflet lobing (leaflets never leaflets often not lobed (except the base leaflets often leaflets not present) lobed (diversely sometimes cordate lobed (diversely lobed so) or auriculate) so) Leaf Alternate, Alternate Alternate, Alternate (rarely Alternate, Almost always arrangement opposite, or opposite, whorled, opposite, in opposite, or alternate whorled or fascicled Cabomba, whorled (opposite or Calycanthus, and whorled in some Asarum) aquatics, whorled in some Liliaceae, Trilliaceae, Orchidaceae) Leaf Cauline scale Basal Cauline (or basal Cauline (or basal Cauline or basal Cauline or basal disposition leaves (basal quill in Zamiaceae and in Nymphaeaceae leaves in Isoetes) Cycadaceae) and Brasenia) Leaf venation A single Complex and 1° and 2° veins 1° and 2° veins unbranched vein variable, often pinnate or parallel or penni- with some palmate, ultimate parallel, smaller dichotomous veins netted or veins cross-veins portions free at right angles Reproductive Spores, borne in Spores, mostly Seeds, borne Seeds, borne in Seeds, borne in Seeds, borne in structures sporangia axillary borne on the naked on scales, fruits fruits fruits to scale leaves (or undersurface of or in berry- or in Isoetes leaves, but also in drupe-like embedded in the a variety of structures base of quill specialized leaves) structures (but not as in Lycophytes) Perianth N.A. N.A. N.A. Typically many- Typically 4-5- Typically 3- merous, the merous merous, the segments borne (sometimes segments in spirally or in many), the whorls whorls segments in whorls # of carpels N.A. N.A. N.A. Typically > 6 Typically 4-5 or Typically 3 (rarely 1-6) 1-2, sometimes (rarely 1, 2, 4, or many, very 6) rarely 3 Carpel fusion N.A. N.A. N.A. Usually separate Usually fused, Always fused (sometimes fused) sometimes separate Perianth N.A. N.A. N.A. Perianth segments Perianth Perianth connation typically separate segments often segments (fused in fused, but also typically separate Nymphaeaceae or often separate (sometimes Aristolochiaceae) fused) 1 Plant minute, consisting of filaments or thalli, generally a single cell thick, usually with abundant single-celled gemmae, a free-living fern gametophyte, superficially resembling bryophytes in lacking vascular tissue, reproducing only vegetatively (by gemmae); [usually growing on vertical or overhanging bedrock (epipetric)]; [Pteridophytes] ............................................................................................................................. ................................................................................... Key A1 – pteridophytes reduced to thalloid or filamentous, free-living gametophytes 1 Plant more complex, with stems (or rhizomes), leaves, roots, the leaves generally > 1 cell thick (except in sporophytes of Didymoglossum, Crepidomanes, Vandenboschia, and Hymenophyllum), with vascular tissue, reproducing by seeds or spores (and often also with various vegetative means of reproduction); [growing in very diverse habitats, including epipetric on bedrock]; [Lycophytes, Pteridophytes, Gymnosperms, Monocots, Basal Angiosperms, and Eudicots]. 2 Plants floating aquatics, never rooted to the substrate (though sometimes stranded by dropping water levels); plants often thalloid in structure (lacking clear differentiation of stems and leaves) .................................................................................. Key C1 – floating aquatics 2 Plants terrestrial, wetland, or aquatic, normally rooted to the substrate (sometimes becoming detached and then floating in the water column, though usually not on the water surface, and lacking obvious adaptations for surface flotation); plants generally with clear differentiation of stems and leaves (with some exceptions). 3 Plants woody, either trees, shrubs, lianas (woody vines), subshrubs, or rosette shrubs, with perennating structures (buds) borne on long- lived, above-ground, woody stems or caudices. 4 Leaves absent or highly modified, the stems themselves fleshy and broadened, the nodes scattered on the flattened pads and bearing glochidia and also often spines ............................................................................................................................................. Key D – cacti 4 Leaves present; stems normal. 5 Plants rosette shrubs or subshrubs, the leaves strongly basally disposed and few to many (the above-ground stem short, usually < 1 dm tall); leaf arrangement alternate (but often with very short internodes).