Mammoth Cave Area Flora
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A guide to area sunflowers ​and similar yellow flowers in the Asteraceae

For a printable Word document of this page, click here.


​Almost all of the species listed below have more than one common name. Latin names are the only way to reliably differentiate them. Phyllaries are the green bracts directly beneath the yellow flower heads.
​


​Real sunflowers are in the genus Helianthus.


​Annual sunflower - Helianthus annus
​
Large flowers with dark centers; these are naturalized cultivated sunflowers. Highly variable, with heights ranging from 3 to 10 feet.


​Ashy sunflower - Helianthus mollis
​
uncommon; easily identified by the white-hairy stem and the clasping, heart-shaped leaves; stands 2 to 3 1/2 feet tall, with 15 to 25 rays.

Eggert's sunflower - Helianthus eggertii 
​
this rare 2 to 4-foot plant has a very smooth, blue-purple stem, which is usually unbranched. Leaves are opposite, stemless, and pointed.

Forest sunflower - Helianthus decapetalus 
​
common; stands to 5 feet high in moist soil; upper leaves, opposite or alternate, have long, tapering, winged stems. Phyllaries are pointed and hairy.

Hairy sunflower - Helianthus hirsutus 
​
very common in our area; stands to 5 feet high in open areas and roadside clearings; stems are covered with stiff hairs; upper leaves are usually opposite, sometimes alternate; leaves have very short or no petioles (leaf stems).


​Jerusalem artichoke - Helianthus tuberosus 
​
uncommon, late-flowering, standing to ten feet; large leaves, up to eight inches, are very coarse.


​Maximilian's sunflower - Helianthus maximilianii 
​
uncommon; this western U.S. species has become naturalized in our area;​alternate leaves are linear and hairy

Rough-leaved sunflower - Helianthus strumosus 
​
uncommon; 
distinguished by a combination of short-petioled and slightly-toothed leaves, and smooth, green stems. Phyllaries are rounded and uneven.

​Sawtooth sunflower- Helianthus grosseratus
​
Uncommon, standing to 8 feet; leaves are narrow and toothed; stems are smooth and frequently reddish.

Small-headed sunflower - Helianthus microcephalus 
​very common; smooth stems are branched near the top, and numerous flowers are smaller than other sunflower species

​Western sunflower - Helianthus occidentalis 
​uncommon; easily identified by its almost total lack of stem leaves. One or two pairs of small opposite leaves are borne on a five or six-foot stem.

Woodland sunflower - Helianthus divaricatus 
​common; distinguished by smooth, sometimes waxy, stems, and sessile (stemless) or nearly sessile leaves.


​Ox-eye (or false) sunflower, genus Heliopsis, differs from all species in the genus Helianthus by its fertile rays. Each ray petal has a small, forked style at its base.


​Ox-eye sunflower - Heliopsis helianthoides. Check flowers for forked styles on the ray petals; leaves are opposite.


​Members of the genus Silphium all have stiff recurved sepals (green petals) beneath the yellow flower head.

​
​
​Compass plant - 
Silphium laciniatum
​
an uncommon prairie species, rare in our area. stem leaves are deeply lobed.


Cup plant - Silphium perfoliatum  
common on riverbanks; upper leaves on this eight-foot plant are fused across the stem.


​Prairie dock - Silphium pinnatifidum
​
rare prairie species; basal leaves are deeply lobed and may be as large as two feet in length

Whorled rosinweed - Silphium trifoliatum 
​
very common in open fields; leaves are typically borne in whorls of three, but may be opposite or occasionally alternate.


​Other yellow summer flowers in the Asteraceae.



​Bear's foot - Smallanthus uvedalia
​grows to nine feet high, forms thickets at field edges; leaves are maple-like.

Gray-headed coneflower - Ratibida pinnata 
​very common in open fields; flower centers are grey-brown; petals are highly recurved; leaves are deeply cut; similar to the following species but more delicate, standing three to five feet high.


​Tall coneflower - ​Rudbeckia laciniata grows to ten feet in moist soils and along the Green River; leaves are deeply lobed; petals are recurved.


Crownbeard (early summer) - Verbesina helianthoides 
​common; winged stem; alternate, pointed leaves

Crownbeard (fall) - Verbesina occidentalis​
​common, and similar to the other crownbeard; differs in flowering season; this species has rounder, opposite leaves

​Yellow wingstem - Verbesina alternifolia
​
abundant plant of wet fields and riverbottoms. Petals are recurved; central disc flowers protrude.


​Tickseed-sunflower - Bidens aristosa
​
late summer flower of open fields; has 8 to 12 green phyllaries beneath the yellow petals. Leaves are highly dissected.


​Ozark tickseed-sunflower - Bidens polylepis
​
common species of wet fields and road edges; very similar to Bidens aristosa, but has 12 or more phyllaries

Prairie golden-aster - Heterotheca camporum
​
an uncommon central U.S. species which is becoming naturalized in Kentucky; hairy stems; alternate leaves; bushy.

To comment or contribute, contact Steve Kistler at kistlers76@gmail.com