Xanthium spinosum L.Asteraceae, (Sunflower Family)Native, Worldwide
Spiny Clotbur |
September Photo
Plant Characteristics:
Much-branched, 3-10 dm. high, to 15 or more dm. wide; lvs. lanceolate,
entire or few toothed or lobed, 3-8 cm. long, 6-25 mm. wide, subglabrous or
strigulose above, silvery-tomentulose beneath, armed with 3-forked stout yellow
spines 1-2.5 cm. long in their axils; male fls. rusty-pubescent; invol. of the
female heads enclosing the 2 florets and becoming an indurated bur; burs many,
but not very crowded, cylindric, ca. 1 cm. long, puberulent, the 2 beaks
inconspicuous and unarmed, the body puberulent and beset with numerous uncrowded
slender sharply hooked prickles; corolla and pappus none.
Habitat:
Common weed of old pastures and waste places at low elevs., cismontane;
to the Atlantic Coast; Santa Catalina and San Miguel Ids.
July-Oct.
Name:
Greek, xanthos, yellow, from
the ancient name of some plant, the fr. of which was used to dye hair.
Latin, spina, thorn, spine. (Jaeger
244).
General:
Rare in the study area having been found only in the canyon northerly of
the Newporter Inn. An immature plant was found in September 1990.
However when I returned to see if it had bloomed, the entire plant was
gone and no others could be found. Fred
Roberts at the UCI Museum of Systematic Biology recognized the foliage; so
identification was possible. A fire
swept through this entire canyon in late June burning everything down to the
edge of the fresh water marsh and even some of that perished.
It has been interesting to watch the new growth of plants along the marsh
edge where there is moisture as they, for the most part, started their life
cycles several months later than usual. Many
plants have reached maturity and others probably will before it turns cold in
late October and November. (my
comments). There
are two seeds in each bur. They
retain their vitality for many years, lying dormant in the thick-walled bur.
This and other species of Xanthium
are poisonous to cattle, sheep, horses, hogs and chickens.
They are most poisonous in the seedling stage.
The seeds are also toxic. The
burs cause serious mechanical injury, and lower the value of wool.
(Robbins, et al. 508).
Two species worldwide. (Hickman, Ed. 359).
Text Ref:
Hickman, Ed. 359; Munz, Flora So. Calif. 241.
Photo Ref:
Sept-Jan 90,91 # 5,6,7.
Identity: by Fred Roberts.
Computer Ref:
Plant Data 410.
Have plant specimen.
Last edit 10/21/02.
September Photo