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 already moved a number of former Senecio members into the Packera and Ligularia genera and many prominent botanists now accept at least some portion of these splits.  Most botanists still do, however, retain the Senecio genus with many of its members.

    The following list of characteristics which separate Senecios from Packeras and Ligularias is mostly in Weber's words from his Colorado Flora.  

    1) Weber separates Ligularia from Packera and Senecio as follows:

Ligularia has turbinate, nodding, succulent heads; succulent, coarsely toothed, often purplish, and clasping leaves; Ligularia roots are little branched and ropy; and Ligularia plants have a strong lemon scent.  

Packera and Senecio have none of these characteristics.

    2) Weber separates Packera from Senecio as follows:  

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 has entire to deeply cut basal leaves only rarely with hard, thick, very fine teeth along the margin.

Senecio leaves are entire or may have backward curving teeth or small callous teeth on the margins. 

Packera plants are often no more than half a meter tall.

Senecio plants are commonly over a meter. 

    The plants that we now label "Senecio" are variable in growth characteristics and can be difficult to identify.  All Senecios pictured on this web site 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 white, tiny, hair-like growth at the apex of the seeds in Asteraceae.

Subalpine, alpine. Disturbed areas, meadows, openings. Summer.
Roaring Fork Road, July 26, 2004.
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.  At top left is a small portion of a colony along the Roaring Fork Road and below that is 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 flower petals.