Orthophytum humile occurs close to rivers and streams in the municipal district of Grão Mogol, many times associated with white-ants, together with other species of Bromeliaceae, as Vriesea oligantha (Baker) Mez and O. aff. mello-barretoi L.B. Sm.
BRAZIL. Minas Gerais: Cristalia and Grão Mogol. It inhabits rupestrial fields about 850-1.000 m.s.m., at the edge of streams or rivers, as a rupicole, associated white ants in the cracks in the rocks.
Orthophytum humile: an Endangered Species of Brazilian Flora. by Otavio Batista de Castro Ribeiro and Claudio Coelho de Paula in J Brom Soc 58(3): 101-4. 2008
The genus Orthophytum Beer is endemic to the northeastern and southeastern regions of Brazil, with a center of diversity along the Espinhaco Range, in the states of Bahia and Minas Gerais (Wanderley 1990; Leme 2004; Versieux and Wendt 2006). The members of this genus are rupicolous, saxicolous, or terrestrial, frequently found in open places that have much light and dry soil, on top of the rocky outcrops of the grasslands of rocky soils in the Espinhaco Range, in the scarps of the Atlantic Rainforest or in the domains of the Caatinga (Smith and Downs 1979)
There are 53 known species of Orthophytum and seven varieties (Louzada 2008), forming two easily distinguished groups: one with a well-developed scape, informally called "complex with scapose inflorescence," and the other group with a sessile inflorescence (Leme 2004, 2004a). The taxonomical problems involving Orthophytum are largely derived from the shortages of good herbaria collections and limited field investigation. The majority of the characteristics of the species are lost in herbaria specimens, especially in the congested inflorescence of the scapeless taxa (Wanderley and Conceicao 2006).
Orthophytum humile L.B.Sm. is one of the most delicate members of the genus, with a restricted distribution in the municipalities of Grao Mogol, the type region, and Cristalia, both in Minas Gerais state (Louzada, 2008). It propagates by means of short stolons, with rosettes 10-25 cm. in diameter and filiform leaves with appressed trichomes and marginal spines about 2 mm. in length. When in bloom, the rosettes exhibit a greenish-white coloration forming a narrow inner ring around the green in¬florescence and an outer much broader ring of pink color, contrasting with the green to purplish distal portion of the leaves. (Figure 1).
The grasslands on rocky soils of the Parque Estadual da Serra de Grao Mogol is characterized by the predominance of deciduous shrub vegetation among large rocks of sandstone (Figure 2) streaked with coarse sand and deposited with (Pirani, Mello¬Silva et al. 2003). Its species are typically xerophytes with numerous Cactaceae, as well as typically xerophytic Bromeliaceae like Dyckia and Encholirium.
The rocky outcrops in the area of occurrence of O. humile are made up of sand¬stone rocks approximately 5 m in height with a large number of concavities and cracks, where the species is established on shallow organic material.
Practically all of the individuals of O. humile are inter-twined with tunnels made by termites, which was also reported by Louzada (2008) (Figure 4). It has been ob¬served that the termites do not eat any parts of O. humile. According to Thorne et al. (Thorne, Haverty et al. 1996) these foraging tunnels link the distant colony to the foraging area and are made by partially digested plant material, fecal material, soil, and water. Apparently the termites are not damaging the root system of the bro-meliads, and their association may favor the nutrition of the plant. In contrast, the spines of the bromeliad can discourage predators of the termites, as observed with Dyckia and Encholirium in the Brazilian grasslands of rocky soils (Thorne et al., 1996). Studies aiming to clarify, the relationship of the termites with this species are impor¬tant to help its conservation.
Orthophytum humile is included on the List of Endangered Species of the Brazilian Flora, together with another four Orthophytum species, under the "Deficient Data" (DD) category. This categorization was made despite O. humile being included in the List of Endangered Species of the Extinction of the Fauna and Flora of Minas Gerais categorized as "Critically in Danger" (CD) because of its limited area of occurrence (Fundacao Biodiversitas, 2007). Even considering its habitat in the State Park of Serra de Grao-Mogol, created in 1998, O. humile is not fully protected due to the periodic fires that affect the local vegetation during the dry season. —SeeLouzada 2008
