Earth Fruit (Geocarpon minimum)

Other Names
Geocarpon, Tinytim
Texas Status
Threatened
U.S. Status
Threatened, Listed 6/16/1987
Description
A small (1-4 cm tall), ephemeral, succulent winter annual that usually completes its life cycle within a 4-week period in the spring. Young plants are grayish; mature plants reddish-purple. Flowers are inconspicuous. This unusual species comprises the monotypic genus Geocarpon.

Taxonomic description: Glabrous winter annual, stems simple or branched at the base, the branches few, erect or spreading ascending, mostly 3-4 cm high and less than 0.5 mm thick, often a bright pinkish or reddish or pale purplish color. Leaves simple, opposite, green or pinkish in color, 3-4 mm long, narrowly oblong or ovate-oblong, the margins entire, and the apex acute. Flowers usually axillary, regular, funnelform-campanulate; sepals 5, 3-4 mm long, reddish or reddish-green; petals absent; stamens 5; staminodes 5; ovary superior, lance-ovoid, somewhat trigonous, about the length of the sepals. Fruit is a capsule containing numerous, long-funicular seeds.
Habitat
In Texas, Geocarpon minimum occurs in a saline barren complex at the vegetative (micro-flora) edge of saline 'slicks' (barren spots), just above the floodplain of the Neches River. The vegetative edge is sometimes called a cryptogrammic lip,' referring to the lichen species and Nostoc sp. that concentrate at the edge of the slicks and the lack of competition with the micro-flora at the vegetative edge of the slicks. The local soils are not mapped at this level of detail but appear to be clay pans, holding late winter rains with a spongy feel to the soil and drying off quickly into a hard cement. The topography also includes mima mounds with micro highs and lows. The site is dominated by micro flora. The saline slick barrens are primarily devoid of vegetation.
Distribution
Found in southwestern Missouri (Dade, Polk, Greene, and Lawrence Counties). Historically found in St. Clair & Jasper Counties, Missouri. Found in three southeastern counties in Arkansas (Cleveland, Drew, and Bradley) and one northwestern County (Franklin). Also found at two locations in Louisiana (Wynn Parish). In early 2004, confirmed in northeast Texas (Anderson County).
Threats and Reasons for Decline
A major threat to Geocarpon is the destruction or adverse modification of its habitat. In Missouri, some sites have been damaged by trampling and grazing by cattle. It has been suggested that physical disturbance may actually benefit Geocarpon at some sites by maintaining bare substrate for seedling establishment. A more serious threat is from pasture improvement with the subsequent invasion by prairie species. ORVs have also damaged Geocarpon habitat. In southern Arkansas much of the habitat suitable for Geocarpon has been heavily disturbed by silviculture, pasture, agriculture, and road expansion.
Other
Flowering: Late February through March.
Illustrations: Line drawings appear in Steyermark (1963). A black-and-white photograph is provided in Steyermark, Voigt & Mohlenbrock (1959). In March 2004, a color photograph appeared on the website of the Center for Plant Conservation.

Portions of text copyright © 2005 NatureServe, 1101 Wilson Boulevard, 15th Floor, Arlington Virginia 22209, U.S.A. All Rights Reserved.
References
  • Behnke, H.D. 1982. Geocarpon minimum: Sieve-element plastids as additional evidence for its inclusion in the Caryophyllaceae. Taxon 3(1): 45-47.
  • Bogle, A.L., T. Swain, R.D. Thomas, and E.D. Kohn. 1971. Geocarpon: Aizoaceae or Caryophyllaceae? Taxon 20(4):473-477.
  • Bridges, Edwin L. 1986. Population Inventory and Monitoring of Geocarpon minimum at Warren Prairie Natural Area. Arkansas Natural Heritage Commission, Little Rock, Arkansas.
  • Federal Register. 1987. Endangered and Threatened Wildlife and Plants; Threatened Status for Geocarpon minimum. Vol. 52, No. 115, Tuesday, June 16, 22930-22933.
  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
  • Kral, R. 1983. A report on some rare, threatened, or endangered forest-related vascular plants of the South. U.S. Dept. of Agriculture Forest Service Technical Publication R8-TP2, Athens, GA. 1305 pp.
  • Kurz, D. Assistant Chief, Natural History Division, Missouri Department of Conservation.
  • Mackenzie, K.K. 1914. A new genus from Missouri. Torreya 14:67
  • McInnis, N.C., L.M. Smith, and A.B. Pittman. 1993. Geocarpon minimum (Caryophyllaceae), new to Louisiana. Phytologia 75(2):159-162.
  • Morgan, Sherry 1980. Status report on Geocarpon minimum in Missouri. Missouri Department of Conservation, Jefferson City, Missouri. 16 pp.
  • Morgan, Sherry 1986. A study of a population of Geocarpon minimum in Missouri. Missouri Department of Conservation, Jefferson City, Missouri.
  • Orzell, Steve L. and Edwin L. Bridges. 1987. Further additions and noteworthy collections in the flora of Arkansas, with historical, ecological, and phytogeographical notes. Phytologia. 64(2):81-144.
  • Palmer, E.J., and J. Steyermark. 1950. Notes on Geocarpon minimum MacKenzie. Bull. Torrey Bot. Club 77:266-273.
  • Pittman, Albert B. 1988. Identification, Survey and Evaluation of Potential Habitats of Geocarpon minimum MacKenzie in Arkansas. Arkansas Natural Heritage Commission, Little Rock, Arkansas.
  • Rettig, J.H. 1983. A New Arkansas station for Geocarpon minimum MacKenzie (Caryophyllaceae). Bull. Torr. Bot. Club. 110(2):213.
  • Shephard, William 1987. Monitoring of Geocarpon minimum at Warren Prairie Natural Area in the Spring of 1987. Arkansas Natural Heritage Commission, Little Rock, Arkansas.
  • Steyermark, J., J.W. Voigt, and R.H. Mohlenbrock. 1959. Present biological status of Geocarpon minimum MacKenzie. Bull. Torrey Bot. Club 86: 228-235.
  • Steyermark, J.A. 1963. Flora of Missouri. Iowa State Univ. Press, Ames. 1728 pp.
  • Thurman, C.M. 1989. Final Report. A Missouri survey of six species of federal concern. Missouri Dept. of Conservation. 99 pp.
  • U.S. Fish and Wildlife Service. 1987. Threatened status for Geocarpon minimum. Federal Register 52(115): 22930-22933.

Back to Top
Back to Top