This variety was found near the coast in a dry valley of the Rio Chancay in the province of Cajamarca in North Peru. This valley is named Sta. Cruz valley in the literature, because it crosses the Andes, from the Pacific towards the settlement Sta. Cruz at the top. The new variety is found at an elevation of only 500-1200 m and grows together with T. lymanii Rauh and the endemic T. latifolia var. leucophylla Rauh.
The plants from the Chancay valley do not grow in small groups on vertical rocks like T. heteromorpha var. heteromorpha, but rather as large distinctive cushions on slightly inclined rock plateaus and on the upper side of large rocks found on the strongly eroded steep walls of the valley on high conglomerate towers. As terrestrials on these slopes, they can grow up to several meters across. Prof. Rauh described a dwarf form growing in the Chancay valley that resembles the highland form. However, the single plants of the new variety are much bigger on average and very different from the highland form with regard to leaf and stem length as well as rosette diameters. Also, the leaves, the inflorescence, the spikes, floral bracts and sepals are longer than with T. heteromorpha var. heteromorpha.
Prof. Rauh points out particularly that "in the original diagnosis nothing was mentioned of the many shapes that the species name suggests". One must also take into account that the plants from the type locality were only known from the specimen Weberbauer 3472, deposited in the botanical museum of Berlin-Dahlem (B). With regard to the population from the Sta. Cruz valley, Rauh (1974: 26) states: '...since the original diagnosis of T. heteromorpha is quite incomplete and little is known about the location details, complementary statements on morphology and ecology shall be made subsequently'. We are reminded of both a similarity and differences with T. tectorum. In T. heteromorpha, the densely arranged trichomes are less eccentric and therefore less spreading. The spikes in T. tectorum are more spreading.
In contrast to the plants of the type population (T. heteromorpha var. heteromorpha), the individuals of the second locality are somewhat similar to T. tectorum in the vegetative stage. Some of the large forms from the Chancay valley actually resemble T. tectorum, because of their leaf length and the relatively large rosettes. Nevertheless, the mostly appressed scales and the shorter inflorescence characterise them without a doubt as specimens of T. heteromorpha.
The plants that grow near the coast differ rather strongly vegetatively from the forms of the highlands, although they do develop an identical inflorescence. It would not be justified, therefore, to treat them as a separate species. The rank of a new variety, however, seems reasonable. This population was named after its discoverer, Prof. Werner Rauh.
The differences between T. heteromorpha var. rauhii and the caulescent T. tectorum var. tectorum are larger than it appears at first glance: The length of the stem widely surpasses the length of the leaves in all forms, but in T. heteromorpha the leaf blades have an almost metallic shine because of the densely appressed scales; the much shorter leaves (1.5-12 cm) are always very dense along the stem, and often (the population at the type locality always) secund, bend upwards. The scape is glabrous; the inflorescence is usually not longer than the leaves and is exceeded at least by the filiform blades of the primary bracts, the compact heads are 20 mm in diameter, only 25 mm long, digitately composed of dense, closely to each other arranged spikes; the primary bracts are almost 2/3 as long as the spikes; the spikes are sessile, only 2.5-3 cm long, 3-(5)-flowered with 2 sterile bracts at the base, very strongly complanate and biconcavely squashed flat in cross-section; the rhachis is strongly flexuous, densely lepidote; the imbricate floral bracts are 18 mm long, i.e. longer than those of T. tectorum, tipped, strongly winglike keeled, the upper half squashed flat in the middle. The flowers are erect, but with a clearly straight tip; the sepals are glabrous or evenly lepidote on the outside, not just scaled on the keels like T. tectorum; the petals are violet, white only at the tips. —SeeDie Bromelie
