Field Trip Texas 0404

Texas, April 2004.

My second visit to Texas had been already planned for some time. While I wanted to study the acacia trees, my wife would look for insects – especially moth and their caterpillars, dragonflies and beetles.

We started our trip from Houston on April 9. The first day was devoted to Brazos Bend State Park. While Hanna was quite successful, I lost my sunglasses. There were no acacias to be found in this area.
Next day we visited Lake Texana State Park north of Victoria. Here I encountered large specimens of A. farnesiana, native to the coastal plains of Texas. One tree was 5,5m high, stretching his crown over appr. 8m. Leaves on secondary branches had 3 pairs of pinnae with 11-13 sets of leaflets. The petiolar gland was in the middle of the petiole. There were no flowers or pods to be seen, and also very few spines. Later I found 2 flowers on another tree. Next to the big tree was a little shrub of A. farnesiana with long ( 2cm) straight white and paired paired spines forming an angle of 100 degrees between them.

Driving further south on US Hwy 77, there were bright yellow blooming trees along the wet edges of the road, but it turned out they were Parkinsonea aculeata (Retama) in full bloom.

The Lower Rio Grand Nat.Wildlife Refuge has several tracts. The Sal del Rey Tract can be accessed from State Hwy 186 near San Manuel. On April 11, nearly all flowers, bushes and trees were in bloom. It was a beautiful view. We took fotos of Palo Verde, Mesquite (Prosopis glandulosa), Retama, Wild olive (Cordia boissieri), Cenizo (Leucophyllum frutescens) , Opuntia, Texas Ebony and of course of the acacia: A.berlandieri still with some flowers and many big (till 11cm long), flat, broad (1,5 cm) pods.
A. schaffneri, identified by the petiolar gland directly below the first pair of pinnae, with a bundle of light red to velvet pods near the ground.
A. wrightii, a shrub 2,3 m high , appr. 4 m wide with light grey bark, showing dark vertical stripes, full of off-white spicate flowers and also flower buds. 1-2 pairs of pinnae and 5 pairs of leaflets on the leaves. The side veines on the backside of the leaflets can be seen clearly. very small prickles.
Reading on my GPS for this location was: Height: 26m; N(latitude) 26.32648; W(longitude) 98.07617.

On April 12 we visited Bentsen Rio Grande Valley State Park south of McAllen. Here we are on the same latitude as Miami, Florida, that means at the southernmost end of the United States. It was warm and humid, and there were lots of mosquitos.
Many A. wrightii were in full bloom with their creamy white spicate flowers. Bipinnate leaves were composed of 2-3 pair of pinnae and 3-5 set of leaflets per pinna.Against the sun the side veins on the back of the leaflets were well visible and could be photographed easily.
On the Rio Grande Hiking Trail, we again found stately A. farnesiana trees with a lot of fat green pods.

The next day we visited Santa Ana Nat. Wildlife Refuge also situated on the borders of the Rio Grande. The plants were the same as in Bentsen S.P.. I took some fotos of  Mimosa pigra var. berlandieri (Zarza; Berlandier mimosa), of Texas Ebony with its zig-zag twigs, showing leaflets similar to the acacias, and of Palo Blanco (Celtis laevigata).

We will now follow the Rio Grande upstream till Big Bend Nat. Park.
The next short stop was at Las Palomas Wildlife Management Area/ Penitas Unit near los Ebanos, where A.farnesiana is abundant,too.Then we drove till Falcon Lake State Park, which has a nature trail. Near the entrance GPS-readings were: Height: 25m; N 26.58359; W 099.14293.
A. rigidula was full of thin, long slightly recurved violet pods. A. berlandieri had some last flowers left, and showed many big green pods.
Mimosa wherryana has leaves like the acacias, but another type of flower and thorny pods.
Aloysia Rio Grande featured white flowers.

In the afternoon of April 15 we reached the Chaparral Wildlife Management Area, where I visited for over one week in February of this year (see separate report).
My first look was for A.angustissima, the Prairie acacia, behind the workshop. And indeed, I found it there: a small (<1m high) brush with big white flowers as well as flower buds, fernlike leaves, showing 3-4 pair of pinnae and appr. 20 pairs of leaflets per pinna. No thorns.

Bees, butterflies and bugs swirled around and specially on the beige spicate ( 1,0-1,5cm long) flowers of A. greggii. Each composite flower contained appr. 20 separate flowers. Leaves had 2-4 (mostly 3) pairs of pinnae and 4-6 small leaflet pairs per pinna. Petiolar gland at 90%, that means shortly before the first pair of pinnae. Petiole 1cm long. Rachis also 1cm long. Alternate prickles (catclaws).

A. schaffneri, which had been in full bloom end of February, showed some last flowers, and not many fruit. Old pods, which had remained on the acacia, showed some outgrowth, looking strange on the bush.

The big A. farnesiana tree near the laboratory was green all over, with some last flowers and some small pods.

In many locations of CWMA, I saw A. berlandieri with still a lot of white globose flowers and flat green pods. The big leaves covered the bushes. A. berlandieri was also abundant at the roadside on US Hwy 277, 5 miles behind Eagle Pass in direction to Del Rio, covering the planes to the north.
Wolf Roland in front of Vachellia berlandieri, Chaparral wildlife Management Area, April 17,2004Wolf Roland in front of Vachellia berlandieri, Chaparral wildlife Management Area, April 17,2004

On April 17, I found a blooming A. neovernicosa for the first time. We walked to the rim of Seminole Canyon in Seminole Historic State Park. The bush was 1,0m high, with reddish brown young twigs, which looked sticky ( I do not know how to prove tackiness in leaves and twigs of this species; I judged it by the reflection of light). Paired, white, 7mm long spines, slighly recurved at the tip. Lots of yellow globose flowers with involucel bracts at appr. 50% (that means in the middle of the involucel) to 65%. Leaves had 1-2 pairs of pinnae with 6-8 pairs of leaflets per pinna. Very slight canal on the petiole, which was 0,7 cm long. Very small gland directly at the point where the first pair of pinnae appears. Rachis 4mm long. Small mucro at tip of leaf. No gland visible on rachis.
A. neovernicosa is the species of the constricta group (A. constricta, A.neovernicosa, A. schottii) which appears most to the East. A.constricta has more pinnae, A.schottii has smaller leaves.

On the plain a lot of blooming bushes resembled acacia, especially concerning the leaves and the prickles. The twigs were grey with horizontal lenticels. But the flower had red calyx leaves and red tips on the stamen – and it had only 9 stamen. Therefore it was mimosa biuncifera.

In Eagles Nest Canyon I took fotos of the Indigo Bush, also called Feather Dalea (Dalea formosa), which has small bipinnate leaves.

We often stop to look at plants near the Highway and search for caterpillars and bugs.
At one place (GPS: Height 308m, N 29.90373, W 101.80667) near US Hwy 90, a blooming acacia bush was to be determined: Is it A. wrightii or A. greggii? The spicate flower had 16 buds, some of them already open. Bipinnate leaves showed 2-4 pair of pinnae and 6-8 pairs of leaflets per pinna. Small gland at first pair and another small gland in front of last pair of pinnae. Mucro; Alternating prickles on twigs at other location than leaves. In one case one prickle was situated just below another – only on the other side of the twig. Young twig red on top and light green below. According to my understanding it must have been A. greggii due to the lower number of pinnae.

Further west on the same highway we stopped at a ridge 2 miles east of the picknick area at Sanderson Creek. On April 18th I found here my first example of A. roemeriana. It can be recognised by the paired prickles in combination with a creamy white globose flower and big leaves and leaflets. The reddish pedicel was 3-3,5 cm long. Leaves had 1-2 pair of pinnae, 5-7 pairs of leaflets per pinna. The 1,5 cm long petiole is clearly canalised. Rachis 1,5 cm long. Leaflets 7-8mm long, 4-5 mm wide, side veines on backside of leaflets visible. 5-7mm distance between the leaflets. Small reddish gland below first pair of pinnae and another gland below 2nd pair of pinnae. Reddish calyx with yellow tips, white stamen with yellow pollen tips.
On the way back we passed through San Angelo State Park on Apr. 26. There I saw A. roemeriana with 1-4 pair of pinnae, 4-8 leaflet pairs per pinna, till 0,8cm long and till 0,3 cm wide; Distance between leaflets 3-4 mm. Distance of leaflets on pinna to rachis was 3mm; Canaliculate petiole 1,5 cm long with gland at 25%; rachis 1,2 cm long; mucro;
paired prickles (catclaws). On young twigs, there was a third prickle in the middle below the paired prickles like in A. senegal.

On April 19, we drove south from Alpine to Big Bend N.P. on Texas Hwy 118. Appr. 10 miles north of Study Butte the landscape had changed to the Chihuahuan desert. Cacti, ocotillo and creosote dominated the country – and all were blooming: a spectacular sight with brown heavy set mountains as a background. And here in Brewster County, A. schottii started to appear. I found a 2m high bush with yellow globose flowers, the involucel bracts at 50% - as typical for the A. constricta group. 1-2 p/p, 4-6 l/p. Leaflets 3mm long and appr. 0,5mm wide.
Paired white spines. Twigs did not seem to be sticky as judged from the (absent) reflection of light.

In Chisos Basin, which is located at an altitude of 1600m, A. farnesiana was in full bloom. Nearby also A. rigidula was blooming.
In Dug-out Wells, I took a foto of a flower of A. farnesiana, which emerged directly from the thick main stem.
At Panther Junction, A. neovernicosa was not yet blooming, but the involucel bracts at 50% could be seen. Petiole 1,1 cm long, Rachis 0,6 cm long, 2 p/pinnae, 2-4 pairs of leaflets per pinna; leaflets were 2cm long and 1 cm wide; mucro; up to 2mm distance between the leaflets. Young twigs seem to be sticky.

At mile 9 on the road from Panther Junction to Study Butte: A greggii in full bloom with 3-5 pair of pinnae and 5-9 leaflets per pair of pinna.

On the trail to Boquillas Canyon of the Rio Grande River some acacia bushes 1,5 m high, were in bloom. Involucel bracts at 50%, very small leaflets, leaflets quite distant from each other, paired white 3cm long spines. Twigs not sticky: probably A. schottii.

Near the Park entrance at Study Butte on mile 17:
Blooming bush with reddish-grey branches. I could not determine any stickiness. The involucel was1,2 cm long with bracts at 50%, yellow globose flowers, bipinnate leaves with 1-2 pair of pinnae, young leaves also had 3 p/p; 3-6 leaflets up to 3mm long and 1 mm wide; Petiole 1,1cm long and narrowly canaliculate, rachis 0,6-1,0 cm long; mucro; paired straight white spines 0,7 cm long.
Below the bush, I found an old recurved pod 5 cm long, 2-3 mm thick, no(?) constrictions, both ends acuminate. Inside a pericarpic strip was visible. It is generated by a white papery layer, which is somewhat smaller than the brown underlying exterior shell. Probably the bush was A. neovernicosa.

On the Chimney Rock Trail, that starts at mile 13 of the Ross Maxwell Drive, I also found small A. neovernicosa bushes with 1-3 pairs of pinnae, mostly 2 pairs of pinnae and 5 pairs of leaflets pairs per pinna; Involucel bracts at 50%; Petiolar gland at 65-85%.
Old pods showed the pericarpic strip.

Finally at km 22 on the Ross Maxwell drive, I saw my first A. constricta at GPS: Height: 698 m, N 29.15125; W 103.50137.
A 2,2 m high bush with reddish-brow twigs, mostly short (0,5 cm), paired white spines. On an old dead twig, the spines were > 2cm long. Bipinnate leaves with 3-5 pair of pinnae, 5-7 leaflets pairs per pinna. Petiole 1,5 cm long, rachis 1,2 cm long; Petiolar gland at 1,2 cm; Mucro. A pod from the last season was 9cm long, strongly constricted between the seeds, 3 mm wide, but only 1mm wide at the constrictions; acuminate. 

On April 24, we visited the Barton Warnrock Environmental Education Center near Lajitas at the Rio Grande. Various acacia species are planted here: A large A. roemeriana tree showed its big fresh violet-green pods.
Here the leaves of A. schottii were so small that they looked from some distance like needles.
The bush was 1m high; 1 pair of pinnae; leaflets 0,5 cm long and 0,05 cm wide; petiole slightly canaliculate, 1cm long; leaflets sometimes not directly opposite of each other; distance between leaflets: 1mm; involucel 5cm long! with only very small bracts in the middle.Old pod brown to black, acuminate at apex, strongly constricted between seeds; seed 0,5cm diameter, grey-brown, with light spot in middle.

There was also A. constricta in bloom and A. neovernicosa: according to the local ranger it has hairs on the leaflets compared to A. schottii, which has no pubescense on leaflets. With my 10x magnifying lens, I could see red dots on the leaflets (from which hairs will emerge??), but no hairs.

In the Barton Center I also fotographed Mimosa biuncifera.

4 miles south of Fort Davis on Tex Hwy 118, there is the Chihuahuan Desert Research institute, which has an arboretum. As the area is situated at an altitude of 1600 m , the development of the acacia bushes was well behind :
A. farnesiana: blooming
A. roemeriana: flower buds
A. constricta: only first leaves appearing
A. schaffneri: showing leaves and first flowers
A. neovernicosa: showing leaves and first flowers
A. rigidula: first leaves

There was also a specimen of Fragrant Mimosa ( mimosa borealis) with flower buds and leaves, and the first flower had opened.

At the end of our trip on April 30th, we were on Harris Ranch near Uvalde, where I had also been in February. We were invited to visit the area by J.W.(Bill) Holloway, Ph.D. Professor, Resident Director of the Texas Agricultural Experiment Station, part of Texas A&M University.
There we saw A. roemeriana, A. wrightii, but above all: A. berlandieri.
GPS: N 29.24901; W 100.10232.
Most bushes were < 1m high, some till 2,5 m high. Fernlike bipinnate leaves with 10 pair of pinnae, not always symmetric. 40 and more pairs of leaflets per pinna. Grey to reddish twigs with scattered prickles. On new growth: small reddish prickles. Also small prickles below the petiole and below the rachis. In some cases no prickles on new leaves. It would be interesting to compare the leaves with those of A. pennata, which are a basis for spicy food in Thailand.

Summarizing I can say, that I saw all acacias, which are to be found in Texas, practically all of them in full bloom or still blooming with fresh pods. The photos should help the visitor of www.acacia-world.net to differentiate and recognize the various acacia species in Texas.
By the way, my wife was also very successful in finding and photographing insects. Moths were abundant at the motel walls in Chisos Mountain Lodge, the Big Bend Motor Inn and at the Comfort Inn in Junction near the Interstate 10.

May 16, 2004