William Weber believes that  "Senecio is [such] an enormous, very unnatural genus....  [that] all of our [North American] Senecio species except the annual Senecio vulgaris... seem destined to be segregated into other genera."  Weber has moved a number of former Senecio members into the Packera and Ligularia genera. Most botanists accept the Packera genus, but almost none accept the Ligularia genus. Instead they keep its members in the Senecio genus.

    The following characteristics (combined from Weber's Colorado Flora, and Packera expert Debra Trock's article in "Sida") help to separate Packera from Senecio. Also see Trock's "The Genus Packera in Colorado".  

Packera leaves have relatively few or no teeth along the margins; Senecio leaves have relatively many teeth along the margins.

Packera plants have basal and stem leaves; Senecio plants may have basal and stem leaves or only basal or only stem leaves.

Packera has horizontal underground stems that root and can produce new plants, i.e., Packera is "rhizomatous"; or Packera has an erect, persistent, woody base (a "caudex"), with branching fibrous roots; Senecio has either a short, coarse, lateral, or almost erect rhizome or has a very short, button-like caudex and has long unbranched fleshy fibrous roots.

Packera flower heads are erect; Senecio flower heads often nod.

Packera phyllaries sometimes have light red tips and are rarely black-tipped, but if they are black-tipped the middle stem leaves are not clasping; Senecio can have prominent black tips and clasping middle stem leaves.  

Packera leaves are reduced in size upward on the stem; Senecio leaves are grouped more toward the top of the stem or are equally distributed along the stem. 

Packera plants are often no more than half a meter tall; Senecio plants are commonly over a meter tall. 

   Senecios are variable in growth characteristics and several of the species can be difficult to identify; others have special characteristics that make them easy to identify.  All Senecios pictured on this website are very common in the mountains and/or canyons of the Four Corners area.

   "Senecio" is from the Latin, "senes", "old man", and refers to the pappus hairs, the tiny bristle, hair, or awn growth at the apex of the seeds in Asteraceae.

   Click for more information about Senecios.

Subalpine, alpine. Disturbed areas, meadows, openings. Summer.
Top photos: Cross Mountain Trail, August 30, 2019; Near Kennebec Pass, September 11, 2019; Colorado Trail above Hillside Road, August 4, 2014; Roaring Fork Road, July 26, 2004; Sharkstooth Pass, September 1, 2015.
Left: Road to Spiller/Helmet Ridge, August 8, 2005.

We like to call this Senecio, "Roadside Senecio", for it is very common in extensive colonies along high mountain roads (and trails) and on edges and ledges, as the top photos on this page show.  At left is a small portion of a colony along the Roaring Fork Road and below that is part of an extensive colony along the road up to the Spiller/Helmet Ridge. 

Senecio atratus is such a tall, robust, attractive plant that it is easy to identify even from a distance: it has tall, nearly vertical leaves, it grows in large colonies, and its leaves are sage-green.  

The leaves appear so sage-green because they are covered with a webbing of fine hairs.  I rubbed downward on the leaf pictured below and a myriad of hairs rolled together revealing a bright green leaf surface.

Subalpine, alpine. Disturbed areas, meadows, openings. Summer.
Road to Spiller-Helmet Ridge, August 8, 2005.

Senecio atratus was first collected for science by Edward Greene in Colorado and he named it in 1896.   "Atratus" (Latin for "clothed in black") refers to the black-tipped phyllaries which form a cup below the yellow ray flower rays.

Subalpine, alpine. Disturbed areas, meadows, openings. Summer.
Upper Calico Trail, July 3, 2013.

This attractive stained glass moth, Gnophaelia vermiculata, is common on Senecio atratus, several other Asteraceae, and other flowering mountain plants.

One of the moth's common names is "Police Car Moth", for its color resemblance to police cars. Notice not only the appropriate police black and white but also the orange (not quite red) under the throat -- the equivalent of the flashing red light atop the police car.

Also notice the feathered antennae, a characteristic that separates moths from butterflies.

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Range map for Senecio atratus