Basic Literatur

Agave titanota Gentry, sp. nov.

Medium-sized, single or sparingly surculose, openly spreading, glaucous white, sub-caulescent rosettes with freely seeding spikes. Leaves broad, linear-ovate, short-acuminate, 35-55 x 12-14 cm, rigid, thick toward base, plane or concave above, convex below, the apex involute above, keeled below, alabaster white, finely granular; margin corneous, widest toward apex (3-5 mm), continuous to base or nearly so, undulate to crenate, the teeth variable, the larger 8-12 (-20) mm long, variably spaced, the leaf apex sometimes toothless for 8-12 cm below spine; spine broadly conical, 3-4 cm long, with deep inrolled groove above, keeled and protruding below, dark brown to gray; spike ca. 3 m tall, erect, the peduncle with deltoid, long attenuate ascending bracts, flowering in upper half of shaft; flowers on bifurcate pedicels 1-2 cm long, 45-50 mm long, yellow or with lavender flushes on tepals and anthers; ovary pale greenish, 22-25 mm long, slender cylindric, with constricted neck; tube 2-4 mm deep, abruptly spreading; tepals 21-24 x 5 mm, ascending, linear, acute, thickly succulent, not clasping filaments at anthesis, the outer 1 mm longer, the inner with prominent keel protruding with apex; filaments 45-55 mm long, flattened, finely tapered toward apex, inserted near rim of tube; anthers 20-23 mm long, regular, centric; capsules (old, weathered), oblong, 2.5 x 1 cm, acute at apex, thin-walled; seed not seen.

Fig. 7.38. Agave titanota. Leaf and leaf margins of three plants, flower cluster, capsules, x 0.5; flower section, x 1.6; 1 capsule, x 1. Drawn from the type collection.

Fig. 7.39. Agave titanota in native habitat at Rancho Tambor in northern Oaxaca, November 1967.

Fig. 7.40. The glaucous white mature rosette of Agave titanota at the same locality.

Type: Gentry & Tejeda 22474. US. isotypes DES, MEXU. Rancho Tambor, ca. 17 miles W of San Antonio, Dist. Teotitlán, Oaxaca, 25 Nov. 1967; elev. 3,200-4,000 feet, cliffs and ledges in limestone canyon. "Rabo de león ceniza."

Planta singula vel surculosa, caule brevi infra rosulam terminalum foliorum vivorum albo-glaucorum. Folia 35-55 cm longa, 12-14 cm lata, lineari-ovata brevi-acuminata rigida, basim versus crassa apicesuperne involuta infra carinata; marginis dentibus prominentibus plerumque 6-12 mm longis, cineras-centibus, curvatura et interspatio variabili; spina terminali 3-4 cm longa, lati-conica, superne canaliculata infra carinata decurrente. Spica erecta densiflora cylindrica scapo incluso ca. 3 m alto; floribus 45-50 mm longis in pedicellis bifurcatis 1-2 cm longis, luteis vel purpureis suffis. Ovarium 22-25 mm longum cylindricum. Tubo 3-4 mm longo expanse; segmentis 21-24 mm longis, 5 mm latis, subequalibus, linearibus acutis crassis, adscendentibus. Filamenta 45-55 mm longa, gracilia tubi orificio inserta; antheris 20-23 mm longis luteis vel purpureis. Capsulae 2.5 cm longae 1 cm latae, oblongae, fragilae. Semina non vidi.

The short spreading tube, long narrow tepals, and high insertion of the filaments relate Agave titanota with the Marginatae. It is distinctive with its broad glaucous white leaves, whence the Greek name signifying alabaster white.

It is known only from the Rancho Tambor, where I noted a large population in the limestone canyon there. Tambor is a watering place for goats until the shallow water hole goes dry after the summer rains. The surrounding country is arid, uninhabited, and covered with an extensive virgin thorn forest, which on some rocky ridges features the distinctive Fouquieria purpusii and many indigenous cacti. Further exploration of this area would likely find other populations of A. titanota. It was called "rabo de león ceniza" by our local constable guide.