Hawaiian Native Plant Genera - Asteraceae
|
|
|
|
|
|
*Argyroxiphium, Dubautia,
and Wilkesia are apparently derived from a single colonization by
an allopolyploid intergeneric hybrid of North American affinity.
|
Argyroxiphium is an endemic Hawaiian genus of five perennial species occurring on
the islands of Maui and Hawaii. Plants mostly sparingly branched or
unbranched, forming one or more, often epigeal rosettes, in flower occasionally
surpassing 2 m in height; leaves liguloid, helically disposed or rarely whorled,
the bases sometimes laterally connate for 1 cm or less. Heads radiate, or rarely some heads apparently
without rays; phyllaries (0)-45, each more or less completely enveloping a
ray ovary; receptacular chaff scales mostly forming a ring encircling
the disk florets, the margins fused into a cup-like false involucre; ray florets pistillate, the
corollas yellow to wine-red or purplish; disk
florets mostly 30-600, perfect, the corollas cream-colored or yellow to wine-red
or purplish; anthers dark purplish black to dark amber; ray cypselae somewhat arcuate, usually ribbed,
sometimes slightly geniculate near apex, 4-14 mm long, the pappus reduced to a minute
coroniform rim; disk cypselae straight to moderately arcuate, mostly 3-8-ribbed,
glabrous, 4-15 mm long, the pappus of 2-10 unequal, minutely fimbriate-margined, somewhat
irregularly coalescent linear-lanceolate to oblong scales, these absent to
poorly developed on the ventral summit but well developed and up to 5 mm long on
the dorsal summit of the cypselae, or rarely reduced to a minute coroniform rim. The chromosome number is n =
14.
Gallery
of Species
Madiinae Access Page
Home Page
