Asteraceae - Tribe Heliantheae

The Heliantheae constitute a very large tribe of Asteraceae with 24 subtribes recognized in the Flora of North America (2006).  Nearly all of the species in 7 of the 10 subtribes illustrated here may be readily recognized due to the association of a receptacular bract or chaff scale with each disk floret in the head (Chaenactinidae, Gaillardiinae, and Pectidinae, mostly lack true chaff scales). The heads usually include bisexual, actinomorphic disk florets with tubular corollas that have 4 or 5 distal lobes and also peripheral zygomorphic female or sometimes sterile florets with strap-shaped corollas that have 3 or fewer distal teeth. However, the ray flowers are sometimes absent and the heads are then discoid, containing only bisexual florets with tubular corollas. The pappus is absent or more commonly ranges from scales to stiff bristles.

Each "thumbnail" image below is linked to a larger photograph.

	Chaenactis cf. carphoclinia, pebble pincushion (Chaenactidinae), vic. Saguaro Natl. Park, AZ, Mar. 2004.
	Bidens amplectens, koko'olau (Coreopsidinae). This Hawaiian endemic species is another typical member of the Heliantheae tribe, although the receptacular bracts aren't obvious in this photo. A common weed, Bidens pilosa, has some populations with discoid heads and others with radiate heads.
	Bidens pilosa, beggars tick (Coreopsidinae). The highly modified calyx or pappus as it is called in this family in this species takes the form of two or three barbed awns at the tip of each ovary. These very effectively increase dispersal of the fruits by mammals and birds.
	Fitchia speciosa (Coreopsidinae). Tantalus, O'ahu, 2005. The deeply cleft zygomorphic disk corollas are unusual for Heliantheae.
	Acmella sp. (Ecliptinae) Note the rayless heads and reddish brown chaff scales (receptacular bracts), one associated with each floret.
	Balsamorhiza sagittata (Ecliptinae), balsam root, vic. Cheney, WA, 2002.
	Calyptocarpus vialis, straggler daisy, prostrate lawnflower (Ecliptinae), UHM Campus, Manoa, HI.
	Echinacea purpurea, echinacea (Ecliptinae), OSU Campus, Corvallis, OR, July, 2003.
	Melanthera (Lipochaeta) remyi, nehe (Ecliptinae). This Hawaiian endemic has female ray flowers and bisexual disk flowers. The upper heads are in an early fruiting stage and show persistent, conspicuous yellowish green receptacular bracts in the center of the heads and darker, purple-marked involucral bracts at the periphery.
	Sphagneticola trilobata (syn. Wedelia trilobata), wedelia (Ecliptinae). Creeping herb from tropical America, with yellow flowering heads, commonly used for a ground cover. This species can hybridize with species in the Hawaiian genus Lipochaeta.
	Zinnia elegans, zinnia (Ecliptinae), annual ornamental species.
	Espeletia schultzii (Espeletiinae), high elevation rosette plants from the Andes, Venezuela.  Some members of this genus have a vegetative habit strikingly similar to the silverswords of Hawai'i (see above).
	Gaillardia aristata, blanket flower (Gaillardiinae). Note the peripheral involucral bracts and 3-notched ray florets, and central disk florets (first photo). In the second photo, the fruits are shattering from the mature head. Each achene has a crown of bristle-tipped scales that represents the modified calyx or pappus. Close attention to the receptacle will reveal the presence of bristly receptacular setae interpreted as enations rather than chaff scales.
	Gaillardia sp. (Gaillardiinae), OSU Campus, Corvallis, OR, July, 2003.
	Helenium autumnale, sneezeweed, (Gaillardiinae), OSU campus, Corvallis, OR, July, 2003.
	Galinsoga quadriradiata, shaggy soldier (Galinsoginae). Manoa Valley, Oahu, Jan, 2000.
	Tridax procumbens, coat buttons(Galinsoginae). The heads on the left have a series of green involucral bracts or phyllaries enclosing two kinds of florets. The 3-notched white corollas at the periphery belong to the zygomorphic female ray flowers. The more numerous yellowish perfect, tubular, actinomorphic flowers in the center are called disk flowers. Each of them has an associated receptacular bract or chaff scale that is not readily visible unless the head is dissected or until it matures and sheds its fruits as is the case with the head on the right. Two achenes (cypsellas) with highly modified calyx (pappus) of pectinate bristles are also visible.
	Helianthus annuus, sunflower (Helianthinae). Note the conspicuous green involucral bracts or phyllaries outside and below the peripheral ray flowers. On the right are several intact disk flowers, each with a greenish corolla tube and 5 yellow lobes. Parts of several florets have been removed to reveal the white, inferior ovaries, a few of which still have one or both of the very pale pappus scales attached to their summits at the flanks of the tiny annular nectary that encircles the scar where the style was attached. The tip of a yellowish green receptacular bract can be seen at the outer or left edge of each ovary in view.
	Scalesia bauri ssp. hopkinsii (Helianthinae).
	Scalesia helleri (Helianthinae).  This genus from the Galapagos Islands shows a radiation of woody forms similar to that seen in the genus Dubautia of the silversword alliance in Hawai'i (see link above).
	Argyroxiphium sandwicense ssp. macrocephalum, Haleakala silversword (Madiinae). The well-known Hawaiian silversword evolved from members of Heliantheae that are found on the west coast of North America. Adaptive Radiation of the Hawaiian Silversword Alliance
	Madia sativa, coast tarweed (Madiinae), vic. Corvallis, OR, July, 2003. More about tarweeds (Subtribe Madiinae)
	Tagetes minuta (Pectidinae).  This tribe consists largely of foetid, often insecticidal herbs, including the cultivated marigolds.
	Tagetes lucida, Spanish, Mexican, or Texas tarragon, Mexican mint marigold (Pectidinae).  Nursery trade, cultivated, O'ahu.
	Rudbeckia fulgida, brown-eyed Susan (Rudbeckiinae), OSU Campus, Corvallis, OR, July, 2003.

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