Overview

Distribution

National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

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Global Range: U. S. historic reports: Alabama, Delaware, Florida, Georgia, Mississippi, Pennsylvania, South Carolina, Tennessee. Extant populations: Kentucky, Louisiana, Maryland, North Carolina, and Virginia. Possibly extirpated from Pennsylvania and Delaware.

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Physical Description

Diagnostic Description

A. obtusifolia differs from A. acuta in that A. acuta has calyx lobes 0.5 to 1 mm long, not or scarcely callose (Pennell 1935). Calyx lobes of A. obtusifolia are minute, 0.05 -0.15 mm. long, subulate, and callose (Pennell 1929). Stems of A. acuta are glabrous; whereas A. obtusifolia has anvil trichomes on the stem surface adjacent to the leaf axil, stem faces, and ridges (Canne-Hilliker and Kampny 1991).

A. obtusifolia differs from A. aphylla in the number of fibers per ridge; obtusifolia having 4 to 20 and aphylla often over 70 (Canne-Hilliker and Kampny 1991). Also A. aphylla has undifferentiated leaf mesophyll whereas in A. obtusifolia the leaf mesophyll is differentiated into palisade and spongy layers (Canne-Hilliker and Kampny 1991, Table 3).

A. obtusifolia can be distinguished from A. oligophylla in that in A. oligophylla the main leaf blades are less than 1 cm. long; in A. obtusifolia are generally longer. The leaves of A. oligophylla contain marginal clusters of sclerids not present in A. obtusifolia (Canne-Hilliker and Kampny 1991, Table 3). A. oligophylla has "bundles of subepidermal fibers at the leaf margins that are contiguous with those on the stem ridges" (Canne-Hilliker and Kampny 1991, p. 1947); A. obtusifolia does not. A. obtusifolia has anvil trichomes on the stem surface adjacent to the leaf axil, stem faces, and ridges; whereas in A. oligophylla they are present only on the stem faces and ridges (Canne-Hilliker and Kampny 1991, Table 5). A. oligophylla is known from Texas (Correll and Johnston 1970), Louisiana, and Mississippi (Canne-Hilliker and Kampny 1991). Consequently, it is sympatric with A. obtusifolia only in the southwestern part of the range of A. obtusifolia.

A. obtusifolia differs from A. skinneriana since the latter has conspicuously striate-angled stems which are scabrellous-roughened. In A. obtusifolia stems are striate-quadrangular, minutely scabrellous on the ridges to almost glabrous. Seed characteristics can distinguish A. obtusifolia from several other species in section Erectae: In A. obtusifolia the pattern of thickenings on the seed coats are sparsely to densely spinulose and the radial walls minutely tuberculate. Whereas in A. skinneriana the thickenings and radial walls are smooth.

Stem characteristics can distinguish A. obtusifolia from A. gattingeri since the former has fiber clusters present in the stem ridges and the latter does not (Canne-Hilliker and Kampny 1991). In addition, obtusifolia has pubescent corollas and gattingeri does not (Canne 1984 ). In A. obtusifolia the pattern of thickenings on the seed coats are sparsely to densely spinulose and the radial walls minutely tuberculate. In A. gattingeri the thickenings are minutely spinulose or sometimes smooth, rather stout and form a swirling, reticulated pattern of polygonal to spindle-shaped interstices and radial walls are minutely tuberculate.

Seed characteristics can distinguish A. obtusifolia from several other species in section Erectae: In A. obtusifolia the pattern of thickenings on the seed coats are sparsely to densely spinulose and the radial walls minutely tuberculate. In A. skinneriana the thickenings and radial walls are smooth. In A. gattingeri the thickenings are minutely spinulose or sometimes smooth, rather stout and form a swirling, reticulated pattern of polygonal to spindle-shaped interstices and radial walls are minutely tuberculate. In A. acuta the thickenings and radial walls are sparsely spinulose. (Canne 1979.)

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Ecology

Habitat

Comments: Agalinis of the section Erectae (which includes A. obtusifolia) occupy dry or seasonally dry habitats (Canne-Hilliker and Kampny 1991, p. 1949) composed of clayey (Radford, Ahles & Bell 1978) or sandy (Gleason and Cronquist 1991) substrates. For A. obtusifolia (sensu stricto) in the Coastal Plain, these habitats can include seasonally wet pine savannas and flatwoods and hillside bogs in pinelands (Godfrey and Wooton 1981). Snider (1969) reported populations (sensu stricto A. obtusifolia and sensu A. decemloba) from soils with pH 4.4 to 5.1; but A. obtusifolia (sensu stricto) also occurs on shallow soil in oolitic limestone in pinelands (Godfrey and Wooten 1981).

Throughout the south it occurs on open sterile soil (sensu A. decemloba) and pinelands of the Coastal Plain (sensu A. erecta) (Small 1933).

In Alabama, it occurs in damp sandy pine woods [Mohr (1901); note information is entered under mistaken application of name 'Agalinis skinneriana Wood', based on bad key in Gray's Manual 6th edition; see Robinson and Fernald (1908, p. 731.)]

In Delaware, A. obtusifolia (sensu A. decemloba) occurs in dry soil, light sand or clay, in the Coastal Plain (Pennell 1913).

In south Florida, A. obtusifolia reportedly grows in "sandy soil , pinelands" (Long and Lakela 1971).

In Kentucky, A. obtusifolia (as A. decemloba) is frequently associated with Aster concolor--both occurring in dry sandy pine barrens (Campbell, pers. comm. 1995). It has been found in dry open woods and edges: a collection in 1929 was from oak-pine woods, in 1934 and 1987 it was found on grassy roadsides--all on dry, sandy ridges in the Southern Cliff Section located along the western edge of the Appalachian Plateau (Campbell et al. 1991). Plants occurring the vicinity of A. decemloba in a roadside patch in Pulaski County include: Pteridium aquilinum var. latiusculum, Asplenium platyneuron, Polystichium acrostichoides, Pinus echinata, Liriodendron tulipifera, Sassafras albidum, Hypericum (Ascyrum) hypercoides, Vaccinium arboreum, Vaccinium vacillans, Rhus copallina, Carya cf. pallida, Acer rubrum var. rubrum, Desmodium marilandicum. Lespedeza intermedia, Lespedeza hirta, Tephrosia virginiana var. virginiana, Galactia volubilis, Quercus falcata, Quercus marilandica, Quercus velutina, Quercus coccinea, Fragaria virginiana var. virginiana, Rubus Argutae (group), Oenothera biennis, Galium pilosum var. pilosum, Pedicularis canadensis, Chrysopsis (Pityopsis) graminifolia, Chrysopsis mariana, Solidago erecta, Solidago nemoralis, Aster undulatus, Aster patens var. patens, Aster concolor, Aster linariifolius, Aster solidagineus, Gnaphalium obtusifolium, Eupatorium fistulosum, Liatris squarrulosa, Prenanthes cf. serpentaria, Smilax glauca, Prunella vulgaris var. lanceolata, Cornus florida, Helianthus divaricatus, Helianthus microcephalus, Helianthus hirsutus, Rudbeckia fulgida var. fulgida, Coreopsis major, Aristida dichotoma, Gymnopogon ambiguus, Erianthus alopecuroides, Andropogon (Schizochyrium) scoparius, Andropogon virginicus var. virginicus, Andropogon ternarius, Sorghastrum nutans, Panicum anceps, Panicum (Dichanthelium) acuminatum (sensu lato), and Panicum (Dicanthelium) dichotomum (sensu stricto).

In Maryland, A obtusifolia (sensu lato) occurs on "dry or moist sandy soils" (Brown and Brown 1984).

In North Carolina, A. obtusifolia occurs in grasslands, waste places, pine woods and savannas within the Coastal Plain; whereas A. decemloba occurs on dry clays and sands of woodland margins in the Piedmont and lower mountains (Radford, Ahles and Bell 1978).

In Pennsylvania A. obtusifolia (as A. decemloba = A. obtusifolia, synonym) recorded from "dry roadside banks and serpentine barrens, parasitic on the roots of woody and herbaceous species. Believed extirpated, Last collected in 1907." (Rhoads and Klein 1993)

Snider (1969) studied two populations of A. obtusifolia (sensu stricto) in South Carolina and measured soil chemistry for pH, magnesium, manganese, calcium, phosphorus, and potassium at their sites [Table 18 in Snider (1969)].

In Virginia, A. obtusifolia (sensu A. decemloba) has occurred in "burnt-out pinewoods" (herbarium specimen Deignan 228 at U. S. National Arboretum Herbarium (NA) filed under Agalinis obtusifolia).

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Population Biology

Number of Occurrences

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 to >300

Comments: This estimate based on unverified historic reports from floras, atlases and herbarium records. Reported distribution and state ranks: Alabama (SR), Delaware (SH), Florida (SR), Georgia (SR), Kentucky (S1), Louisiana (S5), Maryland (S1), Mississippi (SR), North Carolina (S2S3), Pennsylvania (SU), South Carolina (SR), Tennessee (SR), Virginia (S3).

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General Ecology

Persistent populations of Agalinis obtusifolia (sensu A. decemloba) are suspected of being fire tolerant (Campbell et al. 1991). Constraints on populations of this species have not been determined, but short- and long-term maintenance of populations may be related to local edaphic and biological factors that influence seed germination, haustoria formation, pollination vectors, nutrient availability following disturbances, and efficient dispersal to appropriate nearby habitats. Ecological investigations of the population biology of Agalinis obtusifolia (and its morphological variants) at several locations throughout its range would provide the necessary management information needed to conserve this species.

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Life History and Behavior

Life Cycle

Persistence: ANNUAL

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Reproduction

In Agalinis obtusifolia (sensu stricto) plants flower in September and fruit in October in the northern (Fernald 1950) and mid-September to mid-November in the southern (Carolinas) parts of its range (Snider 1969, p. 4). In A. obtusifolia (sensu A. decemloba) plants flower in August and fruit in September in the northern part of its range (Fernald 1950) and flower from mid-August to mid-October and fruit from mid-September to mid-November in the southern (Carolinas) part of its range (Snider 1969, p. 5).

Pollination occurs both by selfing and out-crossing (sensu stricto A. obtusifolia and sensu A. decemloba); specific pollinators for this species have not been documented (but see Pennell 1935); "although insects of the bumble bee (Bombus) type are the primary pollinators of the larger flowered Agalinis species, in the case of A. decemloba the corolla diameter is too small to allow entry of such insects; pollinators quite small in size (3-4 mm) were the only types observed" (Snider 1969, p. 37).

Length of seed viability within a given seed bank is unknown. Characteristics of dispersal and seedling establishment are unknown, however seeds treated with 500 ppm (or possibly less) gibberellic acid solution for 24 hrs at room temperature then placed in 3 degree C (+- 1 degree) growth chamber had germination percentages of 61 to 97 (Snider 1969, Table 17).

No evidence of hybridization between species of Agalinis has been shown to exist (Canne-Hilliker 1987). Chromosome number for A. obtusifolia, A. skinneriana, A. gattingeri, and A. acuta is n = 13 or 2n = 26 (Canne 1984, Table 1).

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Molecular Biology and Genetics

Molecular Biology

Barcode data: Agalinis obtusifolia

The following is a representative barcode sequence, the centroid of all available sequences for this species.


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Statistics of barcoding coverage: Agalinis obtusifolia

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 18
Specimens with Barcodes: 18
Species With Barcodes: 1
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Conservation

Conservation Status

National NatureServe Conservation Status

United States

Rounded National Status Rank: N4 - Apparently Secure

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NatureServe Conservation Status

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: As treated here, relatively common in several states in its broad range in eastern North America.

Continuing disagreements regarding the taxonomic status of this species and its previously separated taxa suggests that further inquiries into taxonomic characteristics are warranted. Intraspecific taxa of this species, if formally designated, could change the global rank for Agalinis obtusifolia or its included taxa.

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Global Short Term Trend: Decline of 10-30%

Comments: No comprehensive assessment of current trends has been undertaken.

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Threats

Comments: Succession for upland site where disturbance regimes have been altered.

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Management

Restoration Potential: The recovery potential of this species is not well known, but it has been assumed to be poor. In fact, Agalinis obtusifolia (sensu A.decemloba) was probably never common in historical times. Pennell (1929), the monographer of the genus, stated that he felt it (sensu A. decemloba) was a waning species. In addition, specific germination and reintroduction efforts have not been undertaken to assess the ability of the species to survive transplanting in the wild. Without detailed research results which delineate the specific habitat requirements of A. obtusifolia, any reintroduction effort will be speculative.

Preserve Selection and Design Considerations: Land protection must be centered around the habitat within which Agalinis obtusifolia occurs. In order to provide adequate protection from pesticide drift, etc., adjacent buffer lands should also be protected.

Management Requirements: Agalinis obtusifolia is a species apparently tolerant and perhaps dependent on slight levels of habitat disturbance for seed germination and growth. Being an annual, these disturbance regimes may need to occur somewhat frequently, if seed longevity is short. In pre-settlement times, this disturbance was likely made by pineland fires and occasionally ungulates or other burrowing mammals. Some extant populations of this species occur in slightly disturbed areas or sterile soils. Due to the loss of the natural fire regime, many historic habitats have become overgrown or offer no seed germination opportunities.

Prescribed burning on a 3-4 year cycle appears to be a realistic management objective for the species as well as for the habitat in which it occurs. Site specific research is needed to provide more detailed management prescriptions within the specific contexts of particular plant communities. All management programs should include a research component to assess the effects of actions.

Management Programs: No management programs are known for this species.

Monitoring Programs: No monitoring program specifically for A. obtusifolia is known.

Management Research Programs: No specific management research program is currently known for Agalinis obtusifolia.

Management Research Needs: Taxonomic uncertainty is perhaps a limiting factor for better understanding the needs of Agalinis obtusifolia and its historically described taxa. Karl Vincent of the New York Botanical Garden, the authority of Scrophulariaceae of Louisiana, is writing the section about Agalinis for the Flora of the Southeastern United States and has extensively studied the systematics of the genus. Contact Karl Vincent, New York Botanical Garden, Bronx, NY 10458. Telephone No. (212) 933-4547. Judith Canne-Hilliker, University of Guelph, Canada, is familiar with the germination requirements of several Agalinis species and has studied the micro-morphological features of the genus that are helpful with identifications. Contact Judith Canne-Hilliker, University of Guelph, Department of Botany, Guelph, Ontario, N1G 2W1, Canada. Telephone No. 519-824-4120, ext. 2767.

Further information is needed regarding basic life history strategies and effects of habitat manipulations on populations of A. obtusifolia.

Biological Research Needs: 1) Taxonomy, classification, herbarium annotations, identification keys based on diagnostic characteristics, and 2) ecological constraints to species: pollination ecology, seed germination ecology, hemiparasitic relationships.

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Relevance to Humans and Ecosystems

Risks

Stewardship Overview: Monitoring needs include the tracking of population abundance and stability with respect to management activities at each site. Research should be centered around the study of species' life history (host specificity, hybridization, pollinator identification, germination requirements, etc.), as well as the production of a search image to survey for additional populations. Management needs include determination of the extent and type of disturbance regime that is most appropriate for the long-term survival of the species and the habitat in which it occurs. Taxonomic research should be coordinated with management to determine the significance of known variations in morphology of this species.

Species Impact: Impacts to other species by Agalinis obtusifolia are unknown, including the potential impacts to hosts because of its hemiparasitic life strategy.

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Names and Taxonomy

Taxonomy

Comments: As treated by Kartesz (1994 checklist), Agalinis obtusifolia includes A. decemloba, A. parvifolia, and A. tenella.

The genus Agalinis has some species for which interspecies boundaries have remained elusive among taxonomists. Karl Vincent of the NY Botanical Garden (pers. comm. to W.R. Ostlie, 1990) believes that Agalinis obtusifolia and A. acuta could be considered subspecies of A. skinneriana.

A word of caution: some plant atlases and floras were compiled based on names and ecological data from herbarium labels taken at face value. Identifications are frequently incorrect in Agalinis --in part based on keys using undiagnostic characteristics. The historic confusion in portions of this genus persists in part through references to unannotated herbarium specimens.

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