Erigeron aureus Greene

October 26, 1959

NEW YORK BOTANICAL GARDEN

02077578

Dr, Andrew Grierson
Royal Botanic Garden
Edinburgh 3, Scotland

Dear Dr. Grierson:

The specimen mentioned in your letter of October 8 is here, and I have been
looking at it. I would call it an unusual form of Erigeron aureus. The relative
sparseness of the pubescence of the involucre is within the limits of variation of
the species as represented in our herbarium. The thing that disturbs me the most
about calling it E. aureus is that the leaves are practically glabrous instead of
being obviously hairy like they ought to be.

The faint purplish streaks on the rays might or might not be significant. I
suspect that the yellow color in the rays of E. aureus is due to anthoxanthins,
chemically closely allied to anthocyanins, rather than to carotenoids. If these
are as unstable as the anthocyanins (and apparently they are) it should not be sur-
prising to find some flecks of purplish in the yellow. What I take to be this same
sort of thing can be seen in yellow cultivars of gladiolus.

It is of course possible that the unusual characters of the specimen are due
to hybridization. E. aureus is known to hybridize with both E. humilis and E. acris,
and it is not impossible that other hybrids might occur. The”’only species near Mt.
Rainier that would be likely to provide the glabrous leaves is E. peregrinus, in the
dwarf alpine phase of ssp. callianthemus that is called var. scaposus. Yet I don’t
quite see this plant as being a first generation hybrid between these two. Inter-
specific hybridization is not particularly common in Erigeron. and I don't know of
any cases of introgression between species that are not so closely allied that they
might be united in an ultraconservative treatment.

In ray opinion field observation and subsequent experimentation will be necessary
to show whether the unusual characters of this plant are due to hybridization or to
some other cause. I am sorry that I can*t be more definite.

Sincerely yours,

AC:gg

Arthur Cronquist
Curator

HERBARIUM OF
THE NEW YORK BDTANICAL GARDEN

PLANTS ?

F WASHINGTON

Erigeron aureus Greene

Specimen raised in Edinburgh from seeds collected on
Burroughs Mountain, Mt. Rainier National Park,
Washington.

Specimen received at New York October 23, 1959«
collected by Mrs. Birdie Pardavich

02077578