Geranium maculatum, spotted geranium
Sullivan, Janet. 1992. Geranium maculatum, spotted geranium. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://research.fs.usda.gov/feis/species-reviews/germac
| Abbreviation | Common Name | Scientific Name | Classification | Status |
|---|---|---|---|---|
| Plants | ||||
| GERMAC | spotted geranium | Geranium maculatum | Life Form: Plants/Forb Kingdom: Plantae Class: Dicot Order: Geraniales Family: Geraniaceae Genus: Geranium | Fed. Protected: No Nativity: Native Invasiveness: Noninvasive |
Taxonomy
The scientific name of spotted geranium is Geranium maculatum L. Named varieties listed by Jones and Jones [22] are as follows:
- Geranium maculatum var. album Lauman
- Geranium maculatum var. plenum Lauman
- Geranium maculatum var. maculatum.
A white-flowered form is listed as Geranium maculatum forma albiflorum House [15,22].
Synonyms
- No entry
Other Common Names
cranesbill, spotted cranesbill, wild cranesbill, wild geranium
General Distribution
Spotted geranium is found throughout eastern North America from southern Ontario south to Georgia and west to eastern Oklahoma and eastern North and South Dakota [15,19,27].
Distribution of spotted geranium.
States and Provinces
- United States: AL AR CT DE GA IL IN IA KS KY LA ME MD MA MI MN MS MO NE NH NJ NY NC ND OH OK PA RI SC SD TN VT VA WA WI
- Canada: ON PQ
Site Characteristics
Spotted geranium is found in woods, coves, thickets, and meadows [15,29]. It appears to prefer more mesic sites such as those found on mid to lower slopes with northern and eastern aspects; preferred soils are clay loam to sandy clay loams and sandy loams [9,20,21,23,27], of average to above-average fertility, and from slightly alkaline or neutral to slightly acidic [7,27,32]. In a study of plant distribution and soil acidity, Wherry [36] found spotted geranium in abundance on a rich bottomland site on Long Island with soil pH of 6.5. Fifty years later, on the same site, Greller and others [18] found that the soil pH had declined to 4.08, and spotted geranium had become a very minor component of the community.
Spotted geranium is abundant in dense patches in natural openings throughout mesic woodlands [27,37]. It is found on sites protected from strong winds, in open shade on hillsides, and on shaded roadsides [32]. Cull [11], working on a project to establish native plants on old highway verges in Illinois, found it already present on the site.
Plant Communities
Jones [20,21] reported spotted geranium as a dominant understory species in a submesic northern red oak (Quercus rubra)/white oak (Q. alba)/wild geranium community type in the hilly coastal plain province of South Carolina. The overstory dominance is shared among northern red oak, white oak, pignut hickory (Carya glabra), and yellow-poplar (Liriodendron tulipifera). The shrub layer dominants are sweet-shrub (Calycanthus floridus) and redbud (Cercis canadensis), with white ash (Fraxinus americanus) in canopy gaps. The ground layer herbaceous dominants include spotted geranium, Christmas fern (Polystichum acrostichoides), bloodroot (Sanguinaria canadensis), lovage (Ligusticum canadense), and cohosh (Cimicifuga racemosa).
In a study relating understory herb distribution to overstory trees, Crozier and others [10] reported that the highest positive association of spotted geranium is with white oak when compared with its other common associates: beech (Fagus grandifolia), yellow-poplar, red maple (Acer rubrum), sweet birch (Betula lenta), black cherry (Prunus serotina), and northern red oak. This association may be a result of higher calcium in the soils under white oaks, due to runoff down the trunk of the tree.
Tree associates in addition to the above named include shagbark hickory (Carya ovata), white ash (Fraxinus americana), eastern hophornbeam (Ostrya virginiana), sugar maple (Acer saccharum), and American elm (Ulmus americana) [4,9,19,20,24].
Common understory associates include Solomon's seal (Polygonatum pubescens), false Solomon's seal (Smilacina racemosa), snow trillium (Trillium grandiflorum), Anemonella thalictroides, common mayapple (Podophyllum peltatus), sedge (Carex spp.), and bellwort (Uvularia grandiflora) [9,10,12,34].
Botanical Description
Spotted geranium is perennial herb 8 to 24 inches (20-60 cm) tall [29]. It grows from a stout, branched, underground rhizome that spreads horizontally up to 6 inches (15 cm). The rhizome bears 10 to 30 sparsely branched roots from the sides and undersurface. Vesicular-arbuscular mycorrhizal structures are present, increasing with decreasing fertility of the soil [7,27,29,32]. A small proportion (4 percent) of populations are male-sterile; these female plants produce an average of 60 percent more seed than hermaphroditic plants [1].
Spotted geranium.
Raunkiaer Life Form (Raunkiaer 1934)
- Hemicryptophyte
- Geophyte
Seasonal Development
The basal leaves of spotted geranium emerge in early spring (around the period of vernal canopy closure) over a period of 4 to 6 weeks, attaining 50 percent of total growth between late April and the first week of May [7]. The stems elongate in April, and blooms appear from April to June, setting fruit 3 to 5 weeks later [27,29,32]. Flower buds are formed in the year previous to flowering and are enclosed in the winter bud. Cauline leaves senesce around October, turning red and yellow, and are lost shortly thereafter. The basal leaves die down in October and November in the midwestern states, later in the southern states [27].
Regeneration Processes
Spotted geranium perennates from a stout rhizome with blunt white tips that hold the following year's bud [27,32]. Fragmentation of the rhizome results in new individuals [28]. Natural stands are mosaics of clones that appear to have enlarged from old, individual plants and persist by vegetative means only [27]. Spotted geranium is long-lived and has a low mortality rate [1]. When crowded, the roots may rise above the soil surface, exposing the buds to freezing [32]. Martin [27] noted that the rhizomes are found at the soil surface (A1 horizon) under closed canopies but in open communities are as deep as 3 to 4 inches (7-9 cm) below the surface.
Young plants usually bloom for the first time in their second or third year but will flower the first year following germination in the greenhouse [27,32]. Production of flower buds, which will expand the following year, takes place when sufficient nutrients are stored [12,27]. Under closed canopies, only 18.8 percent of the plants flower, as opposed to 97 percent in full sunlight [27]. Spotted geranium is self-compatible but depends on pollinators for seed set. The most common pollinators are bees (honeybees, bumblebees) and syrphid flies. Other visitors to the flowers include beetles and ants [1,27,28,37]. Seeds are produced in a dehiscent fruit and are scattered by explosive dispersal an average of 10 feet (3 m) and a maximum of 30 feet (9 m). There is no obvious secondary dispersal vector (i.e. not carried by rainwash or animals) [27,32,33].
Schiffman [31] reported spotted geranium seeds in the seed bank of a chestnut oak (Quercus prinus)/scarlet oak (Q. coccinea) forest. The seed coat is only slightly permeable, and the seed requires stratification before germination will take place. The longer the cold treatment, the higher the germination rate [27]. The seeds can have a dormancy period in excess of 400 days. In a study of savanna restoration, Bronny [8] reported that spotted geranium reappeared when cattle grazing was prevented on an oak savanna site, indicating either its presence in the seed bank or the persistence of rhizomes in the soil.
Successional Status
Spotted geranium is moderately shade tolerant. It is found on disturbed sites, but populations of spotted geranium are best established in open, undisturbed forest [27]. In a study of secondary succession on the New Jersey Piedmont, Bard [4] found populations of spotted geranium on undisturbed sites and did not find it in abandoned fields at any stage of succession. This may indicate that its presence in seed banks is short-lived and/or that spotted geranium is not an effective colonizer.
Immediate Fire Effects
No direct documentation of the direct effect of fire on spotted geranium is available. However, in light of the fact that the rhizome is found at the soil surface under closed canopies and 3 to 4 inches (7-9 cm) deep under open canopies [27], it is reasonable to suggest that the plant is more easily killed by fire where the rhizome is closer to the soil surface.
Postfire Regeneration Strategy (Stickney 1989)
- Rhizomatous herb, rhizome in soil
- Ground residual colonizer (on-site, initial community)
- Secondary colonizer - off-site seed
Fire Adaptations
No entry.
Plant Response to Fire
Spotted geranium increases in abundance immediately after fire [2]. On a site invaded by black cherry and multiflora rose (Rosa multiflora), wild geranium reappeared following a prescribed fire that top-killed the invading cherry saplings [8].
The Research Paper by Bowles and others 2007 provides information on postfire responses of several plant species, including spotted geranium, that was not available when this species review was originally written.
Fire Regimes
For fire regime information, search FEIS for this species by entering the species name on the Advanced Search page and selecting “Fire Regime” as the publication type.
Fire Management Considerations
No entry.
Federal Status
None
Other Status
No entry.
Importance to Wildlife and Livestock
White-tailed deer eat the flowers of spotted geranium. Birds eat the maturing fruits, and Lepidopteran larvae have been observed feeding on the flowers and fruits [1].
Palatability and Nutritional Value
No entry.
Cover Value
No entry.
Value for Rehabilitation or Restoration of Disturbed Sites
No entry.
Other Uses
Extracts of spotted geranium have been used medicinally by Native Americans to treat diarrhea and various mouth ailments. Powdered preparations were used to treat open sores or wounds. The rhizome contains tannic and gallic acids, which contribute to its astringent quality. Clinical trials have shown that tannins promote blood clotting, supporting its use for bleeding sores or wounds [5].
Spotted geranium can be cultivated as an ornamental by transplanting rhizomes or by starting from stratified seed [13,27].
Other Management Considerations
Spotted geranium appears to be dependent on the continued existence of undisturbed stands of mesic, open forests. It is not usually found on disturbed sites [4] and is not noted for rapid colonization [27]. It appears to be sensitive to acidification of soils, and thus areas that are experiencing acid rain are likely to become less hospitable to wild geranium [18].
Spotted geranium is easily cultivated. DeVault [13] transplanted rhizomes of plants growing under closed forest to a fertile, full sun garden. The plants, which had been growing poorly, responded with vigorous growth under garden conditions.
Table A1— Forest and range ecosystems, Bureau of Land Management (BLM) physiographic regions, Kuchler plant associations, Society for American Foresters (SAF) forest cover types, and Society for Rangeland Management (SRM) rangeland cover types in which this species occurs.
Forest and Range Ecosystems (Garrison et al. 1977)
- FRES10 White - red - jack pine
- FRES12 Longleaf - slash pine
- FRES13 Loblolly - shortleaf pine
- FRES14 Oak – pine
- FRES15 Oak – hickory
- FRES17 Elm - ash – cottonwood
- FRES18 Maple - beech - birch
BLM Physiographic Regions (Bernard and Brown 1977)
- No entry
Kuchler Plant Associations (Kuchler 1964)
- K081 Oak savanna
- K082 Mosaic of K074 and K100
- K095 Great Lakes pine forest
- K099 Maple - basswood forest
- K100 Oak - hickory forest
- K101 Elm - ash forest
- K102 Beech - maple forest
- K103 Mixed mesophytic forest
- K104 Appalachian oak forest
- K106 Northern hardwoods
- K108 Northern hardwoods - spruce forest
- K109 Transition between K104 and K106
- K110 Northeastern oak - pine forest
- K111 Oak - hickory - pine forest
- K112 Southern mixed forest
SAF Cover Types (Eyre 1980)
- 20 White pine - northern red oak - red maple
- 21 Eastern white pine
- 25 Sugar maple - beech - yellow birch
- 26 Sugar maple – basswood
- 27 Sugar maple
- 28 Black cherry – maple
- 39 Black ash - American elm - red maple
- 42 Bur oak
- 51 White pine - chestnut oak
- 52 White oak - black oak - northern red oak
- 53 White oak
- 55 Northern red oak
- 57 Yellow-poplar
- 59 Yellow-poplar - white oak - northern red oak
- 60 Beech - sugar maple
- 75 Shortleaf pine
- 78 Virginia pine – oak
- 82 Loblolly pine – hardwood
- 83 Longleaf pine - slash pine
- 108 Red maple
SRM Rangeland Cover Types (Shiflet 1994)
- No entry
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