Silphiums: The Giant Native Plants We All Should Be Growing

This diverse genus provides loads of drama and a plethora of ecological benefits

As a bud horticulturist , my first encounter with prairie bobtail ( Silphiumterebinthinaceum ) was intriguing and enigmatical . The downright size and uprightness of the spade - similar leaves slice up through grasses and forbs captured my vision , and while its place in the University of Wisconsin ’s Curtis Prairie render a clue to its birth , its identity operator was a mystery . Over the ensuing years I total to bang prairie docking facility well , thanks to its outstanding perspective in certain naturalistic country at theChicago Botanic Garden . It honestly delights me in every season . From the unfurling bounce - green leafage to the brown autumnal leave of absence , turn and curling on themselves , to the starkness of the dark , wizened husk poking through a crystalline snowfall , I love this plant life . To this daytime , the sight of its sunny daisies anchored by the prodigious foliage is both nostalgic and inspiriting .

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TRIAL PARAMETERS

Rosinweeds (Silphiumsp. and cvs.)

The Chicago Botanic Garden evaluated 13 rosinweeds between 2002 and 2024 . All specimens were mail ordered except forS. radula , which was wild - garner in East Texas in 2019 , andS. perfoliatum‘The Holy Grail ’ , obtain topically from its conceiver . The seed - grown nature of the coinage describe for use and plant size variations observed within each taxonomic group .

How foresightful : Minimum four eld

Zone:6

Conditions : Full sunshine ; well - drain , alkaline , stiff loam soil

Care : We provide minimum care , allowing the plants to thrive or fail under natural status . Besides observing their cosmetic traits , we monitored them to see how well they grew and adapted to environmental and soil conditions while keeping a close eye on any disease or cuss problems and assessing plant life injury or losses over wintertime .

Top Performers That Make a Bold Statement and Encourage Biodiversity

When it follow to impressive texture , compass plant(S. laciniatum ) is voiceless to beat . This flora features deeply lobed , sandpaper - rough leaves that are big ( 24 inches foresighted and 18 inches wide ) . Like the well - known prairie docking facility , the basal foliage resist vertically . The common name relate to the predilection of the leaf blades , which face east and west to takeadvantage of other dawn and previous afternoon Lord’s Day while debar the desiccating raging midday sun . Flower stem rose to over 8 foot above the tall leafy bases — and all of this with a whole draw of taproot ( 12 feet ) below . These works did get quite wide over time , but some of the girth was due to fore splaying under the weight of the flush . The 4 - column inch yellow salad days — the orotund in the trial — are borne along thick , beet ruby – tinge stems from early summer to mid - fall . The chunky phyllaries are bristly and lack fragrance . reach plant is aboriginal to prairie , glade , and upset habitat from Wisconsin and Minnesota , south to Louisiana and Texas . Resist the urge to put this giant at the back of a layer , border , or meadow — the large leaf is better revalue near the front . And taking a pool cue from its prairie habitat , pair it with grasses and perennial that emphasize the foliage but wo n’t mask the bloom , such as short blue stem ( Schizachyrium scoparium , Zones 3–9 ) , smooth blue aster ( Symphyotrichum laeve , Zones 3–8 ) , and flowering spurge ( Euphorbia corollate , Zones 3–9 ) .

I ’m sticking withprairie dock(S. terebinthinaceum ) as my favorite of this plant chemical group . Once seen , it ’s not blank out — mastering the botanical spelling and orthoepy was a mo of a challenge , though . sullen yellow flowers cupped in smooth unripened phyllaries opened closely a month later than scope plant and had a light overall bloom period . The sylphlike , nearly naked heyday stems were the tallest in our test at 126 inches . The broad Sphyrna tiburo - like basal farewell were 2 groundwork long , or maybe “ grandiloquent ” is a good Bible , as they stand vertically . Like range plant , the thick , sandpapery leaves orient Frederick North to Dixie , thus keep down moisture red ink through transpiration and save leaf surfaces cool to the touch on spicy days . A deep taproot help prairie dock survive uttermost droughts . astonishingly , rabbits and deer now and again munch the rough folio but go out other plants in the trial alone . To be at its best , I feel like prairie bob would prefer lean soil and the company of other plants rather than just hang out by itself . In our prair - ies I love it with efflorescence spurge because the brilliant white cloud of child ’s breath – like flower soften the keenness of the large prairie dock provide . And let the fork-like flower clusters have their infinite by planting fellow closer to the height of the leafy thump . Magenta - flowered winecup ( Callirhoe involucrata , Zones 4–9 ) clambering over and through prairie pier leaf is a particularly brilliant combination . This species is primarily aboriginal to the central United States from Wisconsin in the south to Mississippi .

Roughstem rosinweed(S. radula ) is a standout for a few reason — it blooms later , into later fall here — and its big russet scab - shaped phyllaries are somewhat cool . The bright chicken blossom are 3 to 4 inches across with broad , overlapping rays that make them look more substantial than the spidery blossoms of others in this genus . It ’s also a heavy bloomer , with hundreds of flowers produced at the top . The coarse - textured phyllaries search like green roses before and after unfolding and are quite large at 1½ inches wide . Many of the leafy - stanch rosinweeds drop off their leafage and look a bit ratty by former fall , but roughstem rosinweed ’s stiff , scratchy leaves stayed green longer . At 6½ human foot grandiloquent and almost as blanket , this species is too bragging and bushy for the front of a bed or hayfield . But in the back or middle it mixes nicely with coneflowers ( Echinaceaspp . and cvs . , Zones 3–9 ) , ironweeds ( Vernoniaspp . and cvs . , Zones 4–9 ) , and tall to mid - sized skunk . For a southerly native — South Carolina due west to Texas and S from Missouri to the Gulf of Mexico — it did well in our northerly climate .

| FUN FACT |

Rosinweeds producea sticky substance

A resiny , gumlike material often oozes from theme , flower stalk , and phyllaries , give raise to the group ’s coarse name . Historically , the hardened , gold - colored resin drop were chewed by Native Americans to pick tooth and freshen breather . I call up I ’ll stick with toothpaste !

Whorled rosinweed ( S. trifoliatum ) is probably the best - count rosinweed latterly into autumn because its leave are still mostly fleeceable and stay attached into November ! The scabrous dark green folio are arrange in whorls of three , or sometimes borne oppositely on smooth Bourgogne - ting stems . It has a finer texture than most as the leaves are only 4 column inch prospicient and just over an inch wide . The bushy , vase - shaped habit is attractive , and the tall stems remained upright most of the prison term , although relaxed somewhat during dense peak bloom . The bright yellow blossom are more starlike , since the ray florets do not overlap and are plentiful from early summer to early fall . crowing bluestem ( Andropogon gerardii , Zones 3–9 ) , Melissa officinalis ( Monarda didyma , Zones 4–8 ) , and pitcher sage ( Salvia azurea , Zones 4–9 ) are good match for scale and texture . Whorled Silphium laciniatum is native to prairies and roadside east of the Mississippi River from Pennsylvania and Ohio , in the south to North Carolina and Alabama .

Starry rosinweed(S. asteriscus ) get an honorary credit despite its less than stellar performance . I wanted so ill for it to make my top - picks leaning because of its lemony yellow flower and short height ; there are n’t manySilphiumoptions for pocket-size gardens . regrettably , starry rosinweed was n’t as cold hardy as other species — only one of the five plant endure through 2024 . It is a southern indigen from Tennessee to Florida , and since our seed came from a Florida mail - ordering nursery , we acquire it had a southern provenance . I would like to try cum from a potentially hardier locale — native populations supposedly number as far northwards as southern Illinois . The pollyannaish starlike blossom bloom from mid to late summertime and have 1 - inch - wide-eyed leafy phyllaries with a strong medicative fragrance when bruise or crushed . The 5 - inch green leafage are less uncut than other rosinweed and are coif alternately on burgundy - tint green fore . Try it if you garden in warmer zones , or protect it in colder areas and couple it with mound asters , piddling blue stem , and a short vernonia like ‘ Summer ’s Swan Song ’ .

I admit that loving cup plant ( S. perfoliatum ) fright me a little . It ’s not the ginormous size — that actually intrigues me , as do the conjoined opposite foliage , which take shape cups that hold rain and dew for birds and bee to drink . My jumpiness stems from how quickly and wide it can disperse to form colonies . While I hate to think all it takes to sway me is a little color enhancement,‘The Holy Grail ’ loving cup plantdid just that . The enormous erose leaves are scandalmongering ahead of time in the outflow before fading to chartreuse and then to smart immature from late spring on . yellowish bloom bunch at the top of 10 - foot - tall radical from June 21 to mid - fall ; the 3 - inch flowers are not proportional to the exuberant size !

The phyllaries and stalwart , satisfying stems are hairless , while the big leaves ( 15 inches long and 11 column inch wide ) are rocky . ‘ The Holy Grail’—introduced by Intrinsic Perennial Gardens — has a tighter and more unsloped drug abuse than the species , which is aboriginal to wet places from Quebec to Georgia , and west to Nebraska and Kansas . It is best in orotund bed and meadows or near water , plant with other wet devotee such as Joe Pye weed ( Eutrochium maculatum , Zones 4–8 ) , queen of the prairie ( Filipendula rubra , Zones 3–9 ) , and ‘ Skyracer ’ empurpled moor grass ( Molinia caeruleasubsp.arundinacea‘Skyracer ’ , zone 5–8 ) .

The smaller height ofMohr ’s rosinweed(S. mohrii ) will invoke to gardeners who might be uneasy about its cock-a-hoop first cousin . At 5 fundament tall and 4 foundation spacious , it was one of the short rosinweeds in the trial . For near three months , begin in other summer , abundant 2 - inch wan yellow prime put on a nice show ( pic p. 48 ) . Their light almond or vanilla scent is an unexpected treat that people and pollinator adore . Mohr ’s gumweed is noticeably fuzzy all over — more so than any other metal money — make the dark-green leaves , stems , and phyllaries await grayish ( photo p. 56 , bottom ) . Unfortunately , it has a mussy downside — the wither ray florets fall and cling to the bleary leaves as does other constitutive rubble . Mohr ’s rosinweed is a prairie native in Tennessee , Alabama , and Georgia , but has been full audacious in the upper Midwest . The shaggy-haired habit can be soften by billowy aster , catmints ( Nepeta racemosaand cvs . , Zones 4–8 ) , and grasses , both little and grandiloquent .

| CULTURE TIPS |

The IN and outs of Silphium laciniatum

Traditionally , this group of plants is low-spirited - maintenance when sited correctly in the landscape painting . The biggest challenge consist in — well , their bigness . The shortest gumweed in our run was still 5 feet tall and nearly as broad , so if you want to grow these native perennial ( and you should ) , you ’ll call for to have enough space . Here are some other thing to notice when it comes to these jumbo plants .

The blooms may be little , but they ’re profuse . The prime — shades from pallid to golden yellowed — have a primal magnetic disc fence in by petal - like ray of light florets and look much like their sunflower ( Helianthusspp . and cvs . ) full cousin . The light beam florets of rosinweeds are fecund and produce seeds , while the disk floret are just for show . peak range from 2 to 4 inches broad and seem undersized on such large plants , but their large teemingness makes up for it .

Mohr’s rosinweed

You ’ll comment the phyllaries . The bloom have large squiffy phyllaries — melt off leafage - like structures that work one or more whorls at once below the flush school principal . Think of a phyllary as a leafy cup that flowers sit within . The character of phyllaries varies by specie and aids in designation .

pollinator are plentiful and divers . Honeybees , aboriginal bees , leafcutter bee , monarchs , Panthera tigris swallowtails , skippers , and fritillary all prey on rosinweed nectar , while birds such as American goldfinches and disgraceful - capped chickadees forage for the seeds . MostSilphiumspecies are also host plants for an mixed bag of butterfly stroke and moth , including the aptly discover genus Silphium moth ( Papaipema silphii ) .

see out for reseeding . Although most of the species are quite racy , there is oneSilphiumthat is bigger ( and more thuggish ) than the rest . Deadheading might be a good idea for loving cup plant ( S. perfoliatum , pictured ) as it can be a vigorous seeder and could quickly overhaul a sizable corner of the landscape painting if not kept in check .

compass plant

Large, deeply lobed leaves of compass plant

| source |

Prairie Nursery , Westfield , WI ; 800 - 476 - 9453 ; prairienursery.com

Camp Creek Native Plants , New Albany , MS ; 662 - 539 - 7175 ; campcreeknativeplants.com

Large, deeply lobed leaves of compass plant

Large, deeply lobed leaves of compass plant

Prairie Moon Nursery , Winona , MN ; 507 - 452 - 1362 ; prairiemoon.com

Native Plants inexhaustible , Fishers , IN ; 317 - 777 - 9469 ; nativeplantsunlimitedshop.com

contribute editor program Richard Hawke is the director of cosmetic plant life enquiry at the Chicago Botanic Garden in Glencoe , Illinois .

prairie dock

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starry rosinweed

Prairie dock has dark yellow blooms on wiry stems.

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roughstem rosinweed flower

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