Flora of North America species comparison

Genera ca. 450, species ca. 3800 (76 genera, 403 species in the flora).

Apiaceae currently are divided into four subfamilies (G. M. Plunkett et al. 2004; C. I. Calviño et al. 2008b; S. R. Downie et al. 2010). Subfamily Mackinlayoideae G. M. Plunkett & Lowry are sister to the rest of the family and are characterized by having fruits that are laterally compressed with fiberlike sclereids in the endocarp, no oil ducts in the intervals between the ribs, and minute or rudimentary oil ducts in the ribs. Members of this subfamily are primarily southern hemisphere in distribution; only Centella within this subfamily is found in the flora area. Subfamily Azorelloideae G. M. Plunkett & Lowry are sister to the remaining Apiaceae, and like Mackinlayoideae, their fruits have fiberlike sclereids in the endocarp and no oil ducts in the intervals between the ribs, but the fruits are dorsiventrally compressed or not compressed and almost always have well-developed oil ducts in the ribs. Also like Mackinlayoideae, Azorelloideae are found primarily in the southern hemisphere; Bowlesia is the only genus within the subfamily found in the flora area. The remaining two subfamilies, Apioideae Seemann and Saniculoideae Burnett, share the synapomorphies of fruits without fiberlike sclereids in the endocarp but with lignified parenchymatous cells in the mesocarp (Calviño et al.). The two differ in that members of Saniculoideae have simple umbels or heads and fruits without oil ducts between the ribs but with well-developed rib oil ducts, and usually without a free carpophore, whereas members of Apioideae usually have compound umbels and fruits with well-developed oil ducts between the ribs and usually no rib oil ducts, and usually with a free, 2-fid carpophore. Saniculoideae are represented in the flora area by the native genera Eryngium and Sanicula and the introduced Astrantia. Apioideae are by far the largest subfamily worldwide and contain the remaining genera in the flora area.

Within Apioideae, the traditional classification based on morphology, especially of the fruits, has been shown by DNA-based phylogenetic studies to be highly unnatural, with most tribes and even many genera polyphyletic (for example, see S. R. Downie et al. 2010). Unfortunately, most of the well-supported clades cannot yet be differentiated morphologically, and therefore no complete phylogenetic classification has been developed. Generic boundaries within this subfamily likely will be revised significantly. These problems are especially true of the so-called perennial, endemic North American (or PENA) clade, which comprises Aletes, Cymopterus, Eurytaenia, Harbouria, Lomatium, Musineon, Neoparrya, Oreonana, Oreoxis, Podistera, Polytaenia, Pseudocymopterus, Shoshonea, Taenidia, Tauschia, Thaspium, Vesper, and Zizia (E. E. George et al. 2014). As currently circumscribed, many of these genera are difficult to diagnose morphologically and therefore challenging to identify using keys; it may be worthwhile trying to key a specimen in more than one genus.

Hydrocotyle, traditionally assigned to Apiaceae or to its own family (Hydrocotylaceae), instead belongs to Araliaceae. See the discussion under that family for more information.

Apiaceae are rich in economically important plants. Well-known food plants include carrots (Daucus carota) and parsnips (Pastinaca sativa), both grown for their roots. Celery (Apium graveolens), fennel (Foeniculum vulgare), and lovage (Levisticum officinale) are eaten for their greens. Many species are used as herbs, spices, or flavorings, including angelica (Angelica archangelica), anise (Pimpinella anisum Linnaeus), asafoetida (Ferula foetida Regel), caraway (Carum carvi), celery, chervil (Anthriscus cerefolium), cicely (Myrrhis odorata), cilantro and coriander (both Coriandrum sativum), culantro (Eryngium foetidum Linnaeus), cumin (Cuminum cyminum Linnaeus), dill (Anethum graveolens), fennel, and parsley (Petroselinum crispum). Many of these species are also used in traditional medicine, as is Centella asiatica. Several genera native to the flora area contain species used for food or medicine by Indigenous Peoples, especially Cymopterus, Ligusticum, and Lomatium; details can be found in the discussions of the relevant species. Some species are grown as ornamentals, especially members of Aegopodium, Angelica, Astrantia, Eryngium, Heracleum, Ligusticum, and Selinum.

Despite so many species being edible, some Apiaceae are notoriously toxic. Some species are poisonous when consumed, notably species of Cicuta and Conium, and possibly Aethusa; Conium maculatum, poison hemlock, is reputed to have been used to execute Socrates. Species of Ammi, Heracleum (especially H. mantegazzianum), and Pastinaca contain furanocoumarins and cause photodermatitis if the herbage is handled and then affected skin is exposed to sunlight.

The Apiaceae have some distinctive morphological features that are described using some terms often unique to the family. Some Apiaceae, especially many species of Cymopterus, Lomatium, and Vesper, produce a pseudoscape, which is a leafless section of stem between the top of the caudex and the level where the leaves diverge (usually at the soil surface but sometimes above ground). The pseudoscape is an annual structure, whereas the caudex is perennial.

Compound umbels in Apiaceae are described as follows. The first order umbel is called the umbel; the bracts subtending it, if any, are called involucral bracts. The second order umbels are called umbellets, their peduncles are called rays, and any bracts subtending the umbellets are called involucel bractlets. In Eryngium, which has heads instead of umbels, involucral bracts subtend the head, and each flower is subtended by a floral bractlet.

Specialized terms are also used to describe some aspects of floral and fruit morphology. The bases of the styles are often swollen; together these swollen bases form the stylopodium. The adaxial surface of the mericarp, where it joins the other mericarp, is the commissure. The schizocarps (and therefore the mericarps) are often compressed, either dorsiventrally (parallel to the commissure) or laterally (perpendicular to the commissure). When the schizocarps are not strongly compressed, their solid shape is described; when they are strongly compressed either dorsiventrally or laterally, their plane shape in the plane of compression (that is, the wider side) is described. Each mericarp usually has five primary ribs: one lateral rib on each edge of the commissure and three abaxial ribs on the side opposite the commissure. Sometimes secondary ribs are found between some or all of the primary ribs. Some or all of the ribs may be corky or winged. Oil ducts, which are most easily seen in a mericarp cross section, are usually found in the intervals between the primary ribs and on the commissure; sometimes, they are also found in the ribs. Those in the intervals and on the commissure are often called vittae in other literature. When the mericarps split from each other, they are suspended from a slender, rigid structure called the carpophore, which may be entire or, more frequently, 2-fid.

The petal apices in most Apiaceae bear a narrow, inflexed portion referred to here as an appendage; the apex itself may be broadly acute to deeply emarginate, and the appendage may be distinct or distally adnate to the petal’s adaxial surface. In a few genera, the petal apices are spreading and obtuse, without the appendage. Petal apices in Eryngium are inflexed but usually are lobed to fimbriate.

Compound leaves are described with the pattern of division (ternate, pinnate, or palmate) given progressively to about three orders, as appropriate. For example, “ternate-pinnate” means that the first order arrangement is ternate with each primary leaflet then being pinnate; if the primary leaflets were instead sometimes pinnate and sometimes 2-pinnate, these leaves would be described as “ternate-1–2-pinnate.” When the pattern of division is constant among numerous orders, the leaves are described as decompound.

Eight genera not fully treated here have been reported from the flora area, but none of their species appears to be naturalized.

Bifora Hoffmann resembles Coriandrum, from which it is best distinguished by lacking sepals (versus sepals well developed) and its schizocarps splitting into mericarps (versus not splitting). Bifora radians M. Bieberstein was reported from ballast in New Jersey, Pennsylvania, and Rhode Island and B. testiculata (Linnaeus) Sprengel from ore piles in Maryland. They differ in that B. radians has bisexual peripheral flowers with enlarged, irregular corollas, staminate central flowers with radially symmetric corollas, and smooth to slightly wrinkled mericarps, whereas B. testiculata has all the flowers bisexual with essentially radially symmetric corollas and strongly wrinkled mericarps.

Caucalis platycarpos Linnaeus was reported from ballast in Pennsylvania. This species would key here to Yabea but differs in having the leaves 1-pinnate with undivided leaflets 10–80 × 5–20 mm (versus 1–2-pinnate with pinnatifid leaflets, the ultimate segments 2–8 × 0.2–2 mm) and mericarps 10–12 mm (versus 3–7 mm).

Cuminum cyminum Linnaeus has been reported from waste areas in Massachusetts and Texas. This species would key here to the group of genera with bristly or hispid mericarps (first lead 8); it resembles Daucus and Yabea in having mericarps with five filiform primary ribs and four prominent secondary ribs but differs from both in that schizocarps are fusiform (rather than oblong or ovoid), and the mericarp secondary ribs are not winged and bear straight bristles that are not barbed.

Helosciadium W. D. J. Koch most resembles Apium, differing in having umbels with involucel bractlets and often involucral bracts (versus bracts and bractlets absent) and entire (versus 2-fid) carpophores. Helosciadium nodiflorum (Linnaeus) W. D. J. Koch [Apium nodiflorum (Linnaeus) Lagasca], which has stems rooting only at the base, umbels with 0–2 involucral bracts, and peduncles shorter than the rays, has been reported from ballast in New Jersey, Pennsylvania, and South Carolina and in streams in the San Francisco Bay area, California. Helosciadium repens (Jacquin) W. D. J. Koch [Apium repens (Jacquin) Lagasca] has prostrate stems rooting at most nodes, umbels with 2–3 involucral bracts, and peduncles longer than rays; it has been reported on ballast from Pennsylvania.

Selinum carvifolia (Linnaeus) Linnaeus, which was reported from a vacant lot in Boston, Massachusetts, resembles some Angelica species with mericarps bearing well-developed abaxial wings, but it can be recognized by its solid (versus hollow) stems that are strongly winged (versus not winged), at least on the distal internodes.

Seseli libanotis (Linnaeus) W. D. J. Koch was reported as a waif from the District of Columbia and Maryland. It would key here to Perideridia, differing most prominently in its caudex covered with the fibrous leaf remains (versus not with fibrous leaf remains) and its mericarps with prominent ribs and papillate and densely pubescent surfaces (versus usually filiform ribs and smooth, glabrous surfaces). It resembles Ligusticum in its fibrous caudices but differs in its well-developed (versus minute or absent) sepals, and papillate, densely pubescent (versus smooth and glabrous) mericarps. In addition, S. libanotis usually has strongly ridged stems, in contrast to the smooth stems of the North American species of both Ligusticum and Perideridia.

Trachyspermum ammi (Linnaeus) Sprague resembles Ammi majus but differs in having its mericarps more prominently ribbed and covered with minute papillae (versus smooth). It is known from a single, old report from disturbed ground in Michigan.

Turgenia latifolia (Linnaeus) Hoffmann was reported from ballast in Pennsylvania and Washington and the margin of a farm field in Oregon. It most resembles Daucus and Yabea (first lead of couplet 8), differing from both in its combination of 1-pinnate leaves with broad leaflets (versus highly divided leaves with narrow ultimate segments) and laterally compressed schizocarps and mericarps with essentially equal primary and secondary ribs all bearing barbed bristles.

In the key to genera of Apiaceae, characters and character states are sometimes used that are included in descriptions of taxa within the relevant genera but not in the generic descriptions themselves. Such characters are not usually found as part of a normal genus description (for example, measurements), but they are included in the key because they are useful for identifying some genera within the family.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Species 102 (102 in the flora).

Lomatium has traditionally been defined as having dorsiventrally flattened fruits with two lateral wings. This contrasts with Cymopterus, which has been defined as having both lateral and abaxial wings. This system worked fairly well, although drawing a clear line between Lomatium and Cymopterus was occasionally difficult (A. Cronquist et al. 1997). Recent molecular phylogenetic research has upset this simple genus concept (E. E. George et al. 2014). Although most taxa traditionally treated in Lomatium form a single clade, some species appear more closely related to Cymopterus or some smaller genera (George et al.). Some species in other genera are most closely related to Lomatium. More information is needed before major revisions of Lomatium or Cymopterus can be done, so the two genera are retained here with minor changes. Certain taxa with wingless, laterally flattened or subterete fruit are here included in Lomatium, for example, Orogenia (L. fusiformis, L. linearifolium), Tauschia hooveri (as L. lithosolamans), and T. tenuissima (L. tenuissimum). Cymopterus planosus (L. planosum), which has abaxial wings, is also included. In addition, one species, L. concinnum, is transferred from Lomatium to Cymopterus (as C. glomeratus var. concinnus).

The common name biscuitroot is applied to many Lomatium species because the thick, food-storing roots of many species have long been eaten by Indigenous Peoples. The roots, shoots, young leaves, and seeds of certain species are traditionally used for food or medicine. Seeds of certain species were, and to some extent still are, stored and traded among people of different Indigenous nations (N. J. Turner 1992, 1997). Perhaps human transport of Lomatium roots and seeds explains, in part, the complex patterns of variation and distribution seen in certain species groups. The major trading center at Celilo Falls on the Columbia River (K. Barber 2005) may have contributed to the high diversity of Lomatium in the region. Klickitat County, Washington, and Wasco County, Oregon, the two counties surrounding the falls, have the relatively high total of 23 Lomatium species each, for a combined total of 27 species. Some Indigenous people express concern that commercial exploitation of certain species for medicinal use has decimated some populations, especially L. dissectum and the closely related L. multifidum, sometimes on traditional gathering sites.

While some Lomatium species are widely distributed, many are narrow endemics, perhaps because of the poor seed dispersal ability of most Lomatium (T. D. Marsico and J. J. Hellman 2009). The rate of describing localized taxa shows no sign of slowing, with 14 species described between 2010 and 2019. Additional unnamed taxa are known but have not been published in time to include here (M. Darrach, pers. obs.; K. Mason, pers. obs.; D. Mansfield, pers. comm.).

Difficult taxonomic problems are presented by widespread, subtly variable Lomatium taxa comprising distinct evolutionary lineages that could reasonably be treated as species or varieties but are difficult to distinguish morphologically (for example, J. A. Alexander et al. 2018; J. F. Smith et al. 2018). This is particularly troublesome in what has been called L. triternatum. Recognizing as many as 11 somewhat cryptic species within the L. triternatum complex may be justified. See discussion under 98. L. triternatum.

This treatment is very much a “splitter’s” treatment, accepting nearly all the taxa that have been recognized by recent authors. This is done for two reasons. First, it is easier to combine descriptions of plants inappropriately split than to separate records of plants inappropriately lumped together. Also, the validity of newly described taxa is established or challenged through the practical experience of field-, lab-, and herbarium-based botanists, and for many of these taxa, not enough time has passed for this collective judgement to coalesce.

The taxonomic literature has far more erroneous Lomatium descriptions than might be expected. No doubt some of the problems result from simple human errors, but a common problem is the inclusion of an unrecognized species within the description of another species. These errors are perpetuated through generations of floras. In this treatment, some of these errors are corrected but no doubt others are introduced.

Identification of Lomatium specimens may require roots (but see the next paragraph), well-developed leaves, fresh flowers, and completely mature fruits. Few specimens have all of these features. To permit identification of incomplete specimens, the identification key provided here emphasizes leaf traits wherever possible. Nonetheless, for some groups, for example, L. triternatum and similar species, mature fruits are necessary for species identification. Some specific problems are explained below. The key is entirely artificial; subkeys do not represent taxonomic or phylogenetic groupings.

Collecting roots aids in identification, but Lomatium are perennial by roots, with some species potentially living for a century or more as judged by leaf scars on the caudex (M. E. Darrach 2014). Digging up a large part of the root kills the plant. Therefore, possible global or local rarity of the taxon should be considered before collecting roots. With this key, it is theoretically possible to identify nearly all Lomatium without using roots. Species with shallow, tuberlike root swellings are grouped in Key C because these species are most easily identified by comparing them to each other, but all these species are also keyed out in later subkeys. Plants can be recognized as being in Key C by observing or collecting the top 10 to 15 cm of root.

The caudex, a compact, vertical, usually perennial, underground stem, can be confused with the taproot because it is usually the same color and width. However, the caudex has leaf scars and often has remnants of leaf bases of previous years. These remnants usually break to form chaffy and chartaceous scales. They may decay to fibers as well, and the difference is sometimes useful. Presence or absence of prominent dead, gray, terete bases of peduncles and/or petioles may aid identification. Cleaning these leaf and peduncle remnants from a specimen removes a useful clue to identification. The first leaves many species produce in spring are straw-colored, bladeless sheaths, which should not be confused with remnants of the previous years’ leaves.

The pseudoscape is an annual stem originating at the top of the caudex and reaching ground level or, in a few species, extending above ground. Plants with a pseudoscape can either be acaulous or short-caulescent. Caulescent plants do not have a pseudoscape and instead have a stem with distinctly separated cauline leaves. If a plant is acaulous with a pseudoscape, then the leaves at the apex of the pseudoscape usually arise at slightly different heights, but sometimes a rosette of leaves may form atop it (as in Lomatium planosum and in some L. erythrocarpum). Short-caulescent plants with a pseudoscape do not form a rosette of leaves atop the pseudoscape. Hidden from the sun, the pseudoscape is usually more or less straw-colored. In L. planosum, the pseudoscape extends above ground and is mostly dark green or purple. Pseudoscapes may be inconspicuous, hidden by persistent leaf bases from previous years or by the sheathing bases of petioles.

Leaf characters distinguish many species in Lomatium. Shapes and sizes are of dried leaves. Leaf blade shape (in outline) can be used to separate species with oblong to lanceolate blades from those with wider (deltate, triangular, ovate, rhombic, elliptic, etc.) blades. The vocabulary used to describe the leaf divisions is complex. As used here, the leaf blade ultimate segment is the smallest unit into which the leaf is divided, unless the smallest units are much smaller than the next larger and seem best treated as teeth, as in L. nudicaule. The terminal ultimate segment is the one located at the apex of the leaf blade. The ultimate segments originate from the penultimate segments, which in turn originate from the antepenultimate segments. The number of leaf blade ultimate segments per leaf reported here is based on small samples of basal leaves with these segments counted (if the number is small) or estimated by counting a sample of the leaflets and extrapolating. These numbers are usually not precise. Correctly assessing leaf divisions of curled up, withered, wilted, or overlapping leaves may not be possible. Specimens should be prepared with at least one well-developed basal leaf lying flat and presented in its entirety. In several species, the leaves die and turn brittle by the time the fruits fully mature. Sometimes the shape of such leaves may be preserved by soaking the leaves before pressing.

Cauline leaves, if present, are usually smaller and less divided than basal leaves, and their petioles are likely to be wholly sheathing even if those of basal leaves are not. Cauline leaves are not described for most species.

The peduncle may be hollow at maturity, but that does not mean it is inflated. Truly inflated peduncles become much wider as they mature, usually wider proximally or distally than in the rest of the peduncle. Rays of the umbel may be webbed at the base, sometimes forming a disc. Such discs are not examples of inflated peduncles.

Involucel bractlets are sometimes deciduous in fruit. Pedicels of staminate flowers occasionally have flattened, scarious margins and look like narrow bractlets.

Flower color is often helpful for identification, although it varies within some species. Recording the color of fresh flowers in the field is important. Yellow flowers often dry white or cream-colored. White flowers may dry cream-colored. In a few species, yellow flowers age purple or vice versa. Many white-flowered Lomatium have purple anthers but yellow-flowered Lomatium have yellow or, occasionally, cream-colored anthers. Because purple anthers retain pigment longer than petals do, sometimes petal color can be determined by assessing the anthers. Anther color may be hidden by abundant white or pale yellow pollen. Sometimes anthers persist into the fruiting stage, often hidden in aborted umbellets or atop developing fruits. If a couplet uses flower color and flower color cannot be assessed, try both leads of the pair; one lead usually yields a satisfactory determination.

In a few Lomatium species, the mericarp abaxial ribs look like thin, low, inconspicuous wings, which may be deciduous as in L. tamanitchii. In L. planosum, the abaxial ribs are as winglike as those of Cymopterus. In a few species, the lateral wings curve downward or in toward the commissure, contributing to the terete shape of such fruits. The fruit wing width to body width ratio is calculated by dividing the width of one wing by that of the body. In many species, the lateral fruit wings are reddish or purplish before the mature fruit dries. Then they usually turn tan. At that point, they are usually much paler than the dark fruit bodies. In a few species, the wings remain dark or the body is pale, and thus the two are similar (although not identical) in color.

Schizocarp shapes are described as seen in the plane of the commissure, regardless of the direction and degree of fruit compression. Mericarp length is the length of the fruit body measured along its midline, but not including any wing lobes off the midline. Mericarp width is measured in the middle third of the mericarp and includes the width of the body and both wings. Mericarps increase in width late in their development, mainly because the wings expand. Therefore, mericarp width, shape, wing width, fruit length/width ratio, and wing/body ratio cannot be reliably assessed on even slightly immature fruit. If at all possible, measure only mature mericarps. However, in Key H, the fact that fruits do not become narrower as they mature may allow identification of those plants with wider fruits, using a length/width ratio from immature fruit. Galled fruits, which can be fairly common in L. klickitatense and L. papilioniferum, in particular, may be unusually short and thick; avoid measuring them.

Cogswellia Sprengel is an illegitimate name that pertains here.

(Discussion copyrighted by Flora of North America; reprinted with permission.)