White vs. Green Ash   Jess Riddle
  Jan 31, 2005 08:10 PST 
I've always focused primarily on species characteristics that allow trees
to be identified at 50+ yards or 60 mph; however, a recent hike with
someone who relies largely on twigs and buds for identification has
shifted my focus some. We were hiking on Wadakoe Mountain (see previous
south Carolina posts for description), and identifying various samplings
by their twigs when the ash in particular caught our attention. Given the
steep slopes and several rich coves present on the mountain, I had assumed
all of the ash were white ash. However, the lateral buds only varied from
sitting on top of the leaf scars to having the lower third of the bud set
down into the leaf scar. That pattern was observed on small ash and one
sprout on a large ash all over the mountain indicating dominance by green
ash. The same species of ash is particularly abundant in some of the
coves around Tamassee Knob. Botanists studying each site have previously
identified the ash as white in both areas. These ash tend to have broader
leaflets and broader bark ridges than young mature green ash I see growing
in floodplains, but the bark matches well with Will Blozan's description
of the green ash bark in the smokies. Also, the habitat may not be as
strange as it initially seems for green ash; sweetgum, paw paw, and
trumpet creeper, all species that thrive in the Congaree, have isolated
occurrences on top of one of Wadakoe's two main ridges, and a broad flat
valley along a large creek, typical green ash habitat, borders the
northwest side of the mountain.

Currently, I lean towards green ash for the reasons listed above, but I
want to be sure given that that identification contradicts previous
identifications and will have have a significant impact on our height
record lists. I've attached a small picture of a twig from a small ash on
Wadakoe. This twig is fairly typical, but some faster growing stems have
finely pubescent, emerald green twigs with similar leaf scars and buds.

 http://www.clemson.edu/champtree/details.asp?treeid=244  

has good pictures
of the bark of one of the large ash on Wadakoe, the South Carolina white
ash state champion.

Jess Riddle

Re: White vs. Green Ash   BRUCE ALLEN
  Jan 31, 2005 08:33 PST 

Jess,

I teach tree ID at Ohio State and we depend on leaf scars. The green ash leaf scare is flat on top, possibly with a little divet for the bud (based on Lucy Braun's Woody plants of Ohio). White ash leaf scars are saddle shaped on top. I always thought I could rely on the bark and green twigs (New Hampshire, Maine, and South Carolina), and form (F. caroliniana, F. profunda). These features are much less distinct in Ohio.

Bruce
white vs. green ash with a little blue thrown in for good measure   Robert Leverett
  Jan 31, 2005 13:05 PST 

Bruce:

   I presume the two species of ash can hybridize, but don't know that
for sure. What's your take on hybridization within the ash genus? In
terms of other hybridizations, how about blue ash? Personally, I think
the blue ash is a totally cool species. In fact, it is WAY COOL. Also,
do you recognize red ash? Or do you consider it a slight variant of
green? If my memory serves me correctly, Lee told me that most
taxonomists no longer recognize red ash as a separate species. Lee?

Bob
Re: white vs. green ash with a little blue thrown in for good measure   Bruce P. Allen
  Jan 31, 2005 15:32 PST 

Bob,

Braun considered Red Ash to be a variety of Green Ash - F. penn. var
penn. Burns and Honkola suggest that green x white hybrids were not
successful, only pumpkin ash hybridized with both. There certainly appears
to be overlap in distinguishing characteristics in Ohio. Blue ash is a
really interesting tree, and quite distinct from the other ashes.

Bruce
Re: white vs. green ash with a little blue thrown in for good
measure
  Lee E. Frelich
  Feb 01, 2005 05:41 PST 

Bob:

That's right. Red ash is not a species.

Green and white ash can be hard to differentiate in some parts of its
range. Although the literature says hybrids are rare, I bet that's because
most people who publish papers don't get out in the field and look very
much. Researchers or silviculturists who examine trees in the field
throughout the range are not very numerous.

Lee
RE: white vs. green ash, hybrids   edward coyle
  Feb 01, 2005 07:12 PST 

Bob,

In my North American Trees book by Preston & Braham, it lists only one
hybrid and intergrade for white ash, and that is Texas ash. Green ash has
none. However in his listing for Pumpkin Ash (Fraxinus profunda), he states
that" based upon the number of chromosomes, some authorities think that
pumpkin ash developed from hybridization between white and green ash."
It is found from SE Va. To central Fla., SW Ind. to S Tenn. With several
disjunct populations even to Ohio and Indiana. It is associated with
lowland, floodplain species.

...

Ed C

RE: White vs. Green Ash   Jess Riddle
  Feb 06, 2005 12:22 PST 

Ed,

I have not made any more progress on resolving this issue. Twig and
fruit features are the primary characteristics used to separate the two
species in most books, and the twigs at the SC sites are certainly
closer to the green ash descriptions. However, Iím reluctant to go
against previous identification, typical habitat preferences, and alter
our lists without more to go on than just the twigs. After looking at
the trees more yesterday at Tamassee Knob the bark does point more
towards green and the twig features appear consistent.

If the trees are in fact green ash, then the tallest white ash in SC
would be a 148í tree on the East Fork Chattooga River, and Mohawk Trail
could again claim the tallest white ash outside the Smokies. The change
would also mean that a tree on Wadakoe Mountain would be the tallest
known green ash.

Jess Riddle