Excerpts from Jim Conrad's
Naturalist Newsletter

from the April 19, 2018 Newsletter with notes taken two weeks earlier during a camping trip in Amistad National Recreation Area nine miles northwest of Del Rio, western Texas, on the border with Mexico
AN OCEAN OF SWEET ACACIA

When I entered west Texas's Amistad National Recreation Area looking for a spot in which to pitch my tent, I beheld what's shown below:

Amistad National Recreation Area, view from the hiking trail between the Visitor Information Center and Spur 454

That's a view from the hiking trail between the Visitor Information Center and Spur 454. There you see how generally flat the landscape is. The reservoir is surrounded by a savanna-like vegetation of low, spreading, widely spaced trees, with clumpgrasses and small shrubs between the trees. The US/Mexico border runs down the reservoir's middle, though everything seen in the picture is on the US side. We're about eight miles northwest of the Texas border town of Del Río, whose Mexican consulate I'd come to visit. The reservoir's high-water mark is about 1124 ft in elevation (343m).

In the above picture notice the golden-hued trees. Those are Sweet Acacias, also called Huisache (we-SACH-eh); it's ACACIA FARNESIANA. It's a tough, ecologically important, remarkably useful tree, but the point I want to make about it now is that when I walked into that desert looking for a place to camp and get a good night's sleep, the whole landscape was not only quiet and inviting, but also dizzyingly fragrant with Sweet Acacia flower perfume.

The trees were golden hued because I'd arrived at the exact peak of Sweet Acacia's flowering season. Not long after the above landscape picture was taken, I'd set up my tent beneath a Sweet Acacia tree and, below, you can see what it looked like above my tent:

Huisache or Sweet Acacia, ACACIA FARNESIANA, flowering branches

That night we had a full moon with the above branches resolving themselves into artfully reticulating silhouettes. In the moist night air, the blossoms' perfume grew even more intoxicating.


from the January 5, 2007 Newsletter issued from Sierra Gorda Biosphere Reserve, QUERÉTARO, MÉXICO
SWEET ACACIAS BLOSSOMING

Sweet Acacia is flowering. A member of the Bean Family and sometimes called by its Spanish name Huisache (we-SACH-eh), it's ACACIA FARNESIANA and it's been flowering ever since I got here. However, nowadays surely it's at its flowering peak, for I can't imagine it getting more loaded with tiny, yellow flowers clustered into globular, mothball-size heads. You can see a zigzagging, flowering branch with 1.5-inch long, white spines and feathery leaves below:

Huisache or Sweet Acacia, ACACIA FARNESIANA

On dry, scrubby, thorny slopes around Jalpan, Sweet Acacia often is the most abundant tree. This is of importance to the local ecosystem, for now we're well into the dry season and most scrub-forest plant species are well into "suspended animation" until rains return. Annual herbs are dead or dying, depending on future rains to sprout their seeds. Many perennials are dying back to their tubers and rhizomes, and many trees are losing their leaves, just as if a northern winter had arrived, though we've not come close to having freezing temperatures here. Even Sweet Acacia is dropping some of its leaflets. Thus very few plants in the scrub zone are flowering -- except Sweet Acacia. Pollinators in the scrub zone have little to work with other than Sweet Acacia, but Sweet Acacia gives them what they need.

Moreover, Sweet Acacia's super-abundant blossoms are sublimely fragrant. Every walk I take Sweet Acacia's perfume wraps itself around me just as generously and disconcertingly as Japanese Honeysuckle's aroma did when I used to write about its effects on me, in April, in Mississippi. Why do the most sublime effluvia usually emit from such bristly or otherwise wild and disreputable sources?

Last Saturday I camped beneath a prodigously flowering Sweet Acacia next to the reservoir. In the afternoon I watched untold numbers of honeybees, beetles and birds working the flower-laden branches. Among the birds mostly there were Blue-gray Gnatcatchers with their long, jerky tails and buzzy calls, but also present were Black- crested Titmice and a sprinkling of warblers, including Wilson's, Townsend's and Black-and-white Warblers. What a city of life that tree was, and I was honored that I could sleep beneath such an important ecosystem citizen.

Others cherish Sweet Acacia's fragrance for different reasons. Some of the finest, most expensive perfumes are based on an essence called "cassie" extracted from Sweet Acacia's flowers. To get cassie, macerate the flowers and mix with melted, purified fats until the fats are saturated with fragrance. Then re-melt the fats, strain and cool. This results in a kind of salve that in some cultures is used as pomade for dressing hair. If alcohol is mixed with the salve and let stand for about a month at below-freezing temperatures the fragrance transfers to the alcohol. When you distill this, the alcohol evaporates leaving a viscous, yellow to brown liquid called "cassie absolute," which is one of the most prized of all perfume ingredients.

Despite Sweet Acacia's abundance, specialists aren't sure where the species' homeland is. Today Sweet Acacia grows throughout the world's tropics, in certain places in Africa and Asia seeming as much at home as it does here. In Hawaii it's considered a threat to local ecosystems. I think the general consensus is, however, that it's a native American.


from the April 4, 2007 Newsletter issued from Sierra Gorda Biosphere Reserve, QUERÉTARO, MÉXICO
SWEET ACACIA'S RESIN TEARS

Now the Sweet Acacias are full of immature, green fruits, as seen below.

fruits of huisache or sweet acacia, acacia farnesiana

Late one afternoon I was taking in my laundry spread to dry on the lower branches of a Sweet Acacia outside my casita when a certain glow caught my eye. It was a gob of hardening, honey-colored resin oozing from the wound of a poorly pruned branch, with late-afternoon sunlight shining through it. You can see it below.

resin from acacia farnesiana

Acacia resin has a long history of usefulness, too. You may have heard of "gum arabic, which is a natural product of the acacia whose Latin name is Acacia senegal. Gum arabic is still used as a natural stabilizer and thickening agent in the food industry, particularly in soft-drink syrups, gumdrops and marshmallows. In the past it was used to adjust viscosity in inks. Gum arabic is normally collected by hand in its dried-hard, amber-like state and is often referred to as a 'tear' -- the very thing shown in my picture. You can read more about gum arabic at http://en.wikipedia.org/wiki/Gum_arabic.

When a wounded tree exudes resin drops, it's doing so because the gummy resin plugs up the plant's severed conducting tissue in a process called "gummosis." Resin is a lot like the clotting agents in our own blood when we cut ourselves,

In this year's January 5th Newsletter I told how some of the world's most expensive perfumes are based on an essence called "cassie," which is extracted from the fragrant, orange-yellow blossoms of the Sweet Acacia -- our most common tree here, and the species my resin "tear" was photographed on. On the Internet I read that in some cases gum produced from Sweet Acacia resin is actually superior to Gum arabic produced commercially from Acacia senegal.

What an amazingly useful plant our most common tree is! Yet I'm unaware of people here using it for anything other than firewood. In fact, I'm told that most folks here are glad to have it cut from their land because the tree shades out grass, which goats like to eat.

You can read a whole page of uses of Sweet Acacia products, including plenty of medicinal ones, at http://www.hort.purdue.edu/newcrop/duke_energy/Acacia_farnesiana.html.