As a long - time avid nurseryman , I take pride in being able-bodied to identify most decorative works on quite a little . But weeds are another matter . Identifying the common plaster cast of boney characters , like chickweed , Lamium amplexicaule , and crabgrass , is no problem . As for more exotic or less common green goddess species , I concede my knowledge is somewhat limited . This shortcoming became seeming this summertime when I give way to recognize a weed with small yellow flowers that popped up in my perennial garden . It looked harmless enough , so I chose to ignore it .
As the days started to grow cool , the yellow blossom on this interloper give agency to clusters of spiky - look seminal fluid with tiny barbs on one conclusion . I discovered the seed when I accidentally brush against the flora . To my botheration , dozens of those footling gibe latched onto my shoe , socks , and blue jean .
My curio about the barbs on those seeds kicked into high gear as I contemplated their form and affair . Lots of plant species worldwide are armed with sharp , pointed process . But why ? What role do they serve ? understandably , this call for a lilliputian sleuthing to witness some answers .
delve into the subject , I see that these outgrowth vary depending on which part of the flora they pass off . I ’ll leave it up to the botanists and forensics expert to reckon outhowandwhenthese social organisation evolved . Whythey evolve seems intuitive . Basically , some of them serve as defense mechanisms to discourage nibbling by herbivores , whereas others evolved as seed dissemination mechanisms .
PRICKLY PLANT STRUCTURES define
There ’s a tendency to refer to any piercing pokey thing on a works as athorn , aspine , or aprickle . While the three term are used interchangeably in free-and-easy conversation , botanically they are not the same . Each is an adaptation of a separate works part .
thorn
Thorns occurin the axil of a leafwhere a branch would ordinarily develop , but or else , terminatein a sharp-worded , heavy , woody full point . They grow from a plant life ’s stem tissue and contain internal vascular tissue paper ( bast and xylem ) . A figure of aboriginal tree species , such as Washington hawthorn ( Crataegus phaenopyrum ) , honey locust ( Gleditsia triacanthos ) , and black locust ( Robinia pseudoacacia ) , evolved with thorn . Many non - aboriginal specie have thorns as well , such as firethorn ( Pyracantha ) and Nipponese flowering quince bush ( Chaenomelesspp . ) .
Here ’s a little known fact : Most citrus trees such as lemons , slaked lime , grapefruits , and oranges have thorns . More surprising , Malus pumila , plum , and pear trees also evolve with irritant , although the miscellany grown today have been bred to be spineless .
SPINES
Spines are derived from a plant ’s foliage tissue paper . They are unshakable , sharp , thin , point structures that map a alter leaf or stipule ( appendage found at the base of a foliage ’s stalk ) . Like thorns , vertebral column also have internal vascular tissue .
In general , thorn are obtain on most cactus specie and on some succulent . A flat , wide leaf can recede a lot of moisture , but when the folio is transformed into a minute spine with a restricted airfoil sphere , the plant is able to cut back water deprivation . Spines help provide a little shade to the plant and that is for certain a useful single-valued function in hot , parched environments . Spines also appear to have evolved as a defense mechanism against birds and animals that would otherwise eat up the plant or endeavor to pull out water from its cell .
Some plants other than cacti species have evolve with spiny outgrowths that are turn up on the boundary or tips of their leaf . For example :
Spinose leaf margin – Some Tree and bush such as holly(Ilex ) specie , put on holly ( Osmanthus ) , and Oregon grape holly ( Mahonia aquifolium ) have barbed edges along the border of their leaves . These bare pricker are extensions of the leaf ’s major vein .
Spinose apical processes – Yet other plants , such as Agave , Sansevieria , and Yucca species , have sharp tips ( final back ) on the ends of their leaves .
PRICKLES
Prickles are short , sharp , woody jut that are derived from a plant ’s skin ( epidermis ) tissue paper , which is the undivided stratum of cells cover the leaves , flowers , stems , and root of sealed industrial plant . Think of it this style : If you encounter a sharp , taper outgrowth anywhere on a plant where a branch or a leafwould NOT normally be , then it ’s very likely to be a prickle . Unlike thorn and spines , prickles do n’t have any vascular tissue connect them to the main body of the flora .
Some plant , like rose George W. Bush , have prickle on thestems only . Oh , by the way of life , the “ spine ” on rose George Herbert Walker Bush are not really thorns at all . Because they grow at random smirch along the stems of the flora , that technically makes them prickles .
Greenbrier(Smilax ) is an example of a plant armed withprickles on its stems . Despite its weediness and unfriendly pricker , this low - spring up woody vine is aboriginal throughout North American and is not without merit . The yield are a food source for many bird species . They eat the fruits and then pass them randomly throughout our landscape painting , which explains why the plants seem to appear out of nowhere .
Other plants , likehorsenettle(Solanum carolinense ) , haveprickles onboth stem and leaves . Horsenettle is a bothersome locoweed that occurs both in pasture fields and in family landscape painting . All part of this plant life — theme , petiole , leaf vein , and even the flush stalking — are embrace with pricker . Because the plant is so prickly , animals are deterred from grazing . As it turns out , this is a upright thing because the plant and their fruits are equal to of poison livestock .
For yet other plant species , theprickles are attached at thebase of the leaves only . Spiny amaranth(Amaranthus spinosus ) is one such example . The very sharp , pissed prickles on this plant can be as long as a quarter of an column inch . As an away , a mature setaceous amaranth plant can produce about 235,000 seeds , make it a formidable green goddess to deal with .
A few plants havereflexed or recurved prickles , meaning that the pourboire point downwardly . This innovation hinders little animate being from climbing stems to get hold of folio on some plants . On other plant , particularly unity with long stem , the prickle design allows the plant to lift onto other subdivision or plants for support . Mile - a - min vine(Persicaria perfoliata ) , which is highly invasive and difficult to eradicate , is an example of a plant with reflexed prickles .
MORE PRICKLY PLANT STRUCTURES
The human race of plant with setose personalities is filled with many that do n’t accommodate neatly into the three categories described above . A few variation on a theme let in the following .
Prickly protrusions on flower heads , seeds , or fruit — From an evolutionary standpoint , such structures make a lot of sense . To ensure the continued survival of their metal money , industrial plant need to disperse their seed to new areas where they will have less competition for light , water , and nutrient . One extremely effective dispersal method involves the use of special barb - like mechanism designed to outfit seed to mystify or hitch elsewhere . According toBotany for Gardenersby Brian Capon , “ The front of hooks and barb is a reliable indication that a seed or yield is waiting to hitch a drive on a go past animal . ”
Here are a few examples of dope equipped for hitch :
Fine hairs or bristle — A keen many plants are cover in hunky-dory hairs or bristles that serve a variety of purposes , let in shelter from heat or stale and protection from herbivores . Prickly lettuce ( Latuca serriola)is such a plant . The leave-taking on this sess have prickly bound accompany by a course of stiff , prickly bristles on the lower midvein . Between the prickly leave-taking and milky sap , this is not a pleasant plant . It is also quite fecund . agree toWeeds of North America , a large , matured plant can produce up to 87,000 seed !
Burs – A burr ( also spelled burr ) is a seed or juiceless yield with hook or tooth that are designed to repel herbivore andtodisperse seeds by latching onto fur or habiliment . Depending on the plant species , burs can be a mild annoyance or a serious chance . On the irritating side , they can snag or tear one ’s clothing . On the serious wild side , some burs can puncture tires , knock off onto the legs or feet of fauna get injuries , and damage agrarian harvesting equipment .
Some plant with bur admit the following :
ET TU , VEGGIES ?
Yes , even vegetables have their plowshare of prickly personalities . Some varieties of eggplant , for illustration , have little prickles on their stems and on the calyx where the yield joins the stem . Grasping the theme at that point in time with bare hands can be painful . jaundiced squashplants have prickly stem and leaf that can be uncomfortable to the touch when handle with bare hands . Even the fruits are covered with fine , nearly transparent hair - like bristles . Some , but not all , cucumbervarieties have more or less prickly fruit as well as prickly stems . Artichokeshave prickly leaves and beautiful violet - purple thistle - similar flower that attract pollinating insect . The edible flower bud is made up of scale of measurement - like leaves with myopic inedible phonograph needle - same thorns on the tips , which must be snip off .
PREVENTION / CONTROL OF PRICKLY plant
Except for the vegetables , many of the barbed works describe herein are opportunists . They appear most often in disturbed soil , such as alongside roadways , construction situation , or garden beds . In plus to being blown about on the wind or carried by pee , seed may also be propagate by wild animals , birds , humans , and our pets . Regardless of how they are dispersed , it ’s authoritative to remove the plant at the seedling microscope stage for several reasons :
THE TAKEAWAY … .
A spikelet is a limited short branch , a spine is a qualify leaf or leaf part , and a prickle is an outgrowth from the epidermal tissue paper of stems , leafage and some fruits . know the distinctions among the three is not essential unless you need to use that knowledge to avail identify industrial plant species . Keep in mind that not all flora with sharp or prickly outgrowths are weeds or even undesirable . Many of these plant species are valuable sources of pollen , nectar or shelter for pollinators and other wildlife . However , it is important to discover those undesirable plant species that should be obviate before they become a pain . Preventing them from position seed in the first piazza or carry off them at the seedling stage are your good choice .
As I muse the beggarticks weed that start me on this path to discovery , I now sympathize and even look up to its survival scheme . The plant is root in the dirt and can not move . So , many millennia ago , its ancient ascendent figured out how to use roving creatures to disperse their seeds for them . There ’s even a terminus for this scheme : zoochory . moderately clever , do n’t you think ?
Featured photo : Common thistle armed with formidable prickles on stem , leaves and heyday . Photo : Pat Chadwick
source :
Botany for Gardeners , Third version ( Capon , Brian , 2010 )
Weeds of the Northeast , ( Uva , Richard , Neal , Joseph C. , and DiTomaso , Joseph M. , 1997 )
smoke of North America(Dickinson , Richard and Royer , France , 2014 ) , The University of Chicago Press
Virginia Weed Identification , Virginia Tech websiteStart – Weed Identification ( vt.edu )
University of Missouri Weed ID usher , https://weedid.missouri.edu/
“ Seed Dispersal,”ivycreekfoundation.org / docs/9.Seed_Dispersal
“ Identification of Virginia ’s Noxious Weeds , ” Virginia Cooperative Extension Publication SPES-244NPhttps://www.vdacs.virginia.gov/pdf/va_noxious_weeds.pdf
Botany 115 Vegetative Terminology , Modified Roots , Stems and Leaves
Of Thorns , Spines and Prickles , University of Missouri Integrated Pest Management article by David Trinklein , published January 3 , 2013 .
