The species was found to be unique chromosomally with a polyploid series of chromosomes (2N = 20, 40, 60). Anthurium gracile  is considered to be one of the most primitive chromosomally of all the species of Anthurium. Numerous pollinations have been made using the pollen of A. gracile but without success. As in section Tetraspermium , the lack of hybrids is not surprising considering the unique chromosome number. Anthurium gracile cannot conveniently be used as a maternal parent, since it apparently is self-pollinating or apomictic.

VIII. DECURRENTIA Schott (Fig. 12)
The section Oxycarpium  was recognized by both Schott and Engler. Schott included three species, one of which, A. oxycarpum , the type species of the section, has proven to be be a member of section Pachyneurium thus requiring a new sectional name for the balance of the group not pertaining to Pachyneurium . The remaining species in Schott's, A. decurrens  Poeppig, was retained by Engler who added also A. pittieri  Engl. and A. guayaquilense  Engl. Schott description of sect. Oxycarpium also does not fit well the balance of the species left after A. oxycarpum is removed. He described plants with short internodes, something often not true of A. pittieri and A. decurrens and also stressed early emergent pistils (something also true of A. oxycarpum but hardly a good character at the sectional level. Still, these two species can not be accomodated in any other section recognized by Engler despite the fact that species like them are reasonably common, especially in South America. Therefore a section must be created to accomodate them. Since A. decurrens was the only other species included by Schott the section will be called section Decurrentia .

Chromosome counts in the section (A. pittieri Engl. and A. pittieri  var. fogdenii  Croat ined.) are 2N=30. Hybrids of A. pittieri  have not been documented.

IX. XIALOPHYLLIUM Schott (Fig. 13-17)
This section as delimited by Engler (1905) seems certain to be an unnatural one with at least two different types of plants involved. Both groups have stems erect or scandent with long internodes and have leaf blades which are typically longer than broad and only rarely conspicuously lobed at the base. Many of these species have thin, veiny, usually matte often somewhat bullate blades and commonly have greenish inflorescences. Most species with known fruits exhibit greenish or yellowish-green fruits. The plants in this group commonly occur at higher elevations though some members may occur near sea level in northwest South America. Examples of species in this group include A. davidsoniae Standley (Fig. 13), A. microspadix  Schott (Fig. 14), A. myosuroides  (H.B.K.) Endl. and A. pallens Schott (Fig. 15).

The remainder of the species placed in section Xialophyllium  tend to have more coriaceous, usually semiglossy to glossy blades which are smooth or at least not markedly veiny or bullate. Examples include A. bredemeyeri Schott (Fig. 16 & 17) A. caucanum Engl. (not as of Exotica 111), A. mindense Sodiro, A. popayanense Engl., A. purdieanum Schott and A. stipitaum  Benth.

Both groups of section Xialophyllium are poorly known horticulturally and the group, albeit an unnatural one, is a relatively large one and deserving of considerably more study.

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