A. Leaves of Agave azurea . 

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... by 14–22 cm wide at widest point just above the middle, 10–17 cm wide at narrowest point below the middle, attenuate at the tip, light bud printing, faint to moderate banding, smooth to slightly rough below, slightly rough and waxy above ( Fig. 4A). Mar- gin straight to rarely undulate, teeth on small teats or no teats, deflexed towards base, orange-yellow, red- dish purple or brownish red, aging to whitish gray, 10–15 mm long, 40–50 mm apart; terminal spine 40–70 mm long, decurrent to the first 1–2 pair of teeth. Inflorescence 2–4.5 m tall (Fig. 5A), infertile part 0.7 to 3 m long, flower-bearing part 1.3–1.5 m long with 6–9 lateral branches each with 6–8 flower-bearing peduncles; bracts on scape 14–17 cm long by 2–3 cm wide at base, 2–3 cm long ter- minal spine, bracts in flower-bearing portion 7 cm long by 4 cm wide, lacking terminal spine. Flowers 79–85 mm long (Fig. 5C), yellow-orange, pedicel 6–30 mm long, 8–14 flowers per umbel (Fig. 5B); ovary inferior, 30–40 mm long; neck 6–10 mm long; tube 9–22 mm long by 15–22 mm wide; inner te- pals 21–29 mm long by 10–13 mm wide, outer te- pals 22–30 mm long by 9–13 mm wide; stamens inserted on rim of tube or 14–15 mm above base of tube, filaments 43–65 mm long, anthers 16–28 mm long, pollen yellow; style 85–90 mm long when fully exserted. Capsules with a 1-5 mm beak, oblong with transverse lineations on the cells, 35–60 mm long by 16–19 mm wide. Seeds black and shiny, lunate to ovate, 5–7 mm long, 4–5 mm wide. In three in- florescences, only a quarter to one-third of the seeds were black (viable). Type locality — Picachos de Santa Clara, east slopes of Mesa la Distiladera, Baja California Sur, Mexico. Latitude N 27.12769°, longitude W 113.59095°, elevation 365 m (Fig. 6). Relation to other species — Table 1 provides a comparison between the three species of Agave ...

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... Vizcaíno Peninsula or its off-shore islands. Agave azurea does not offset, is larger than A. vizcainoensis in most characters, its leaves are significantly differ- ent in shape and margins ( Fig. 5A), and its capsules and seeds are smaller. It is evident that Agave azurea and A. vizcainoensis are closely related, but what is not clear, is the relationship of those two to other species on the peninsula. Gentry (1978, 1982) stated that, because of the deep flower tube, A. vizcainoensis does not show a close relation with other members of the Deserticolae, but he included it in that group for lack of a better option. It is our opinion that these two species appear to form a bridge between the Gentry (1978) groups of Deserticolae and the Umbelliflorae. The shorter, more congested inflorescence shape of Agave azurea (Fig. 4A) is more similar to that of the Umbelliflorae than the narrow, elongated shape of the inflorescenc- es found on members of the Deserticolae. Not only does the deeper tube (Table 1) suggest an affinity to the Umbelliflorae, as Gentry (1978, 1982) noted, but the tepal length to tube length ratio (from less than 3:1 to less than 2:1) is closer to that of the Um- belliflorae (about 2:1) than it is to other members of the Deserticolae (from 3:1 to nearly 5:1). Finally, the overall flower length approaches that of other mem- bers of Umbelliflorae more so than it does for those of Deserticolae. Distribution and climate — This species appears to be restricted to rocky colluvial hillslopes and al- luvial fans in the Picachos de Santa Clara on the Viz- caíno Peninsula, Baja California Sur, Mexico (Figs. 1, 6). We did not find Agave azurea on sandy soils west of the type locality nor in the sandy plains to the east. An aerial survey in December 2012 indicated a large population in the vicinity of the type locality, particularly on the north slope of Mesa la Distiladera, the colluvial slopes and alluvial fans south of Cerro el Cirio, and the north slopes of Cerro el Cardón and Cerro Santa Clara. In addition, from the air we saw scattered individuals on Cerro Victoriano north- east of the main picachos. Temperature and rainfall on the Vizcaíno Pen- insula are poorly known but are highly variable and influenced by seasonal fog and tropical cy- clones. Punta Abreojos, the closest climate station but on the coast of the Pacific Ocean, has a mean annual precipitation of 68 mm with extreme inter- annual variability; the warmest month is Septem- ber (average high: 33.9° C, average low: 18.9° C; php3?s=983047&cityname=Punta-Abreojos-Baja- California-Sur-Mexico&set=metric, accessed 25 September 2013). Temperatures in the Picachos de Santa Clara likely are more variable because they are farther from the moderating effects of the Pacific Ocean, and annual precipitation likely is greater, but probably less than 200 mm. Phenology — We first observed this species in May 2010, and no plants were observed to be flowering. We found flowers on this species in April 2013 (Fig. 4), after Hurricane Fabio (July 2012), Tropical Storm Norman (September 2012), and Hurricane Paul (October 2012) brought what appeared to be con- siderable rainfall and minor flooding to the Vizcaíno Peninsula. Because no plants appeared to be flower- ing in May 2010, our impression is that this species opportunistically flowers, possibly in response to in- cursions of tropical cyclones. Associated perennial vegetation and habitat — Typical perennial species growing with Agave azurea are prominent members of the Vizcaíno subdivision of the Sonoran Desert and include Pachycormus dis- color (Benth.) Cov. var. veatchianus (Kell.) Gentry, Olneya tesota A. Gray, Parkinsonia microphylla (Torr.) Rose & I.M. Johnston, Bursera microphylla A. Gray, Encelia farinosa A. Gray, Larrea tridentata (DC) Cov., Fouquieria diguetii (Van Tieghem) I.M. Johnston, Ferocactus peninsulae (Engelm. ex Weber) Britt. & Rose var. viscainensis (Gates) Lindsay, Cylindropun- tia molesta (Brand.) Knuth var. clavellina (Engelm.) Rebman, Stenocereus gummosus (Engelm.) Gibson & Horak, Pachycereus pringlei (Engelm.) Britton & Rose, and Jatropha cinerea (Ort.) Muell. Arg. in A. DC. Agave azurea is narrowly endemic to an isolated arid mountain range on the Vizcaíno Peninsula well away from metropolitan areas, recreational develop- ment, or other potentially deleterious land uses. The only land use in the vicinity is livestock grazing ...