Imperial Valley press., 1913-09-06
LUTHER BURBANK TELLS
HOW TO MAKE NEW PLANTS

some keen observer. Millions of others
are forever buried in oblivion for the
L. k of such an observer.
But l wish to call attention to not
unusual result of crossing quite dis
tinct wild species which deserves the
most careful analysis, as it seems TO
promise a new text for scientific in
vestigation, especially on biometric
lines. The subject was most forcibly
brought to my attention twenty years
ago by the singular behavior of the
second generation seedlings of rasp-
berry blackberry hybrids. BY crossing
the Siberian raspberry (Rubus crat-
aegifolius) with our native trailing
blackberry (Rubus vitifolius), thor
oughly fixed new species was sum-
marily produced. The seedlings of
this composite Rubus (named Pri-
mus), though most perfect blend of
both parents, but resembling neither,
never reverted either way, all the
seedlings coming much more exactly
like the new type than do the seed
lings of any ordinary wild Rubus.
Many thousand plants have been
raised generation after generation, all
repeating themselves after the new
and unique type. No botanist on earth
could do likewise than classify it if
found wild as valid new species,
which it truly is, though so summarily
produced by crossing.
Since the Primus species was orig
mated, numerous similar cases have
attracted attention, such as my now
popular Phenomenal, produced by
crossing the Cuthbert raspberry with
our native Pacific coast blackberry
and the Loganberry, both Of which,
though a complete blend of two such
distinct species, yet reproduce from
seed as truly as any wild Rubus spe-
cies.
l have also had growing on my
grounds for some fifteen years OF
more hybrids of Rubus idaeus and Ru-
bus villOsus, both red and yellow va
rieties. All are exactly intermediate
between these two very widely differ
ent species, yet both always come true
Intermediates from seed, generation
after generation, never reverting
either way.
BY crossing the great African "stub-
BILE berry" (SOlanum guinense) with
our Pacific coast rabbit weed" (Sol-
anum villosum) an absolutely new
species has also been produced, the
fruit of which resembles in almost
every particular the common blue
berry, and while the fruit of neither
species is edible, the fruit Of the
newly created one is most delicious
and most abundantly produced, and
the seedlings generation after genera
ton, though produced by the million,
still all come as true to the new type
as do either parent species to their
normal type.
Still another example Of this mode
may be found in my experiments with
Opuntias. By crossing o. tuna with
0. vulgaris, thousands Of seedlings
have been produced, all Of which, in
the first, second and third generations
though we'll balanced type of the two
natural species, still come as true to
the newly created species as do either
parent species to their onw natural
types.
Not only does this new mode hold
true under cultivation, but species are
also summarily produced in wild
state by natural crossing.
The western blackcap and the east
ern red raspberry when growing con-
tiguous, as they very commonly do in
Central British America, often cross,
forming an intermediate new species
which sometimes sorely crowds both
Of the parent species, and when
brought under cultivation still firmly
maintain it's intermediate characters,
no matter how often reproduced from
seed. And still further our common
"tarweed" NADIA elegans), with it's
beautiful large blossoms often crosses
with M. saliva with its insignificant
pale yellow flowers, producing a COM
plete intermediate. have not yet de-
termined whether the intermediate
will produce true from seed, but con-
fidently expect it to do so. Similar re-
suits among wild evergreens and de-
cidous trees and shrubs and herba-
ceous plants have been frequently and
forcefully brought to my attention,
leaving little doubt in my own mind
that the evolution of species is by
more modes than some are inclined
to admit