Flowering plant have acquire numerous ways of ensuring that their seeds find competition - free soil and water system . Some drop their seeds into water system for dissemination ; others scatter tiny seeds on the steer . Hooked seeds , orburrs , hitchhike to new locations in pelt or on clothing . burr are such successful adaptations for survival that many plant species with burrs have now become invasive .
Sandburs
one-year field sandbur plants ( Cenchrus spp . ) expand in warm , sandy grunge across much of the United States . These grow up to 20 column inch in meridian and feature article leaf sword with flossy surfaces and fluid undersides . Their round , 2 1/2 - inch Aaron Burr pass off in erect clustering , and have pelt - piercing hooks . From early summertime to mid - descent , the 1- to 3 - foot high coastal , or arena , sandbur ( C. spinifex ) get over-embellished burr with up to 40 hooks each . Upright southern sandbur ( C. echinatus ) has erect , 2- to 6 - in leaves . Its October burrs have 40 to 60 spinal column . Longspine , or mat , sandbur ( C. longispinus ) may be vertical , or spread to form a dense hummock . Its burrs appear from July to September , with as many as 50 hook mensurate 1/5 column inch or longsighted .
Bur-Reeds
Bur - reeds ' ( Sparganium spp . ) straplike gullible leaves grow partially deluge in shallow , fresh water system . These plants thrive in temperate to cool climate . Giant , or broadfruit , burr - reed ( S. eurycarpum ) stand from 1 1/2 to 9 feet high . Its slender branching stems bear as many as six prickly , spherical unripe flower head . The mid- to previous summertime flowers yield to arduous brownish burrs . Narrow - leaved bur - reeds ' ( S. angustifolia ) up - to-3 - infantry stems each bear from two to four spiny , orotund flowers and short - stalked burr . Bur - reeds furnish shelter for legion waterfall species .
Edible Burr Plants
Many burr - bearing plant have seen diachronic use as food . vulgar burdock ( Arctium minus ) , a non - aboriginal plant life to the U.S. , now grows in every res publica but Florida , Alaska and Hawaii . It get a first - year clump of warmheartedness - influence immature leaves . open atop spiny green bracts , burdock ’s second - summer , red - purple flowers give manner to large , conical burrs . Burdock ’s natural spring leaf can be used in salad or as boiled greens ; its summertime roots are also edible after boiling and peeling . Eastern Native American tribes and early settler eat Allegheny chinkapin ’s ( Castanea pumila ) sweet , briary - shell chestnut . This Beech - folk Sir Herbert Beerbohm Tree grows to 30 base high-pitched in sandlike , undetermined woodlands from Massachusetts to Florida and west to Texas . It couple cascading clusters of fragrant , yellow leaping prime with glossy green leaves . Fall leafage varies from yellow to purpleness .
Toxic Burr Plants
Spiny cocklebur ( Xanthium spinosum ) grows as mellow as 5 feet on disturbed territory and croplands across the South . Its 1- to 3 - in , blank - veined green leaf have briery bases . A unmarried plant may have as many as 150 burrs , which can last in the soil for several years . Its seedling and seeds are toxic to pasture animate being , especially squealer and horses . Bur buttercup ( Ceratocephala testiculata ) invades lawns , roadsides , cropland and pastures . The earth - squeeze yearly ’s tiny , yellow blooms look within a calendar month after its antlerlike spring leave issue . They produce tiny , oval burr before the flora expire back in summer . Growing plant life carry skin - irritating sap . They ’re also toxic to foraging animal . symptom of ingestion admit respiratory trouble , frail muscles and looseness of the bowels . Sheep have mellow susceptibleness .
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