Jay F. Bolin

The genus Isoetes is known for morphological convergence and a relative paucity of useful gross morphological characters for identification. Thus, the chromosome complements of Isoetes spp. are key attributes for species delimitation. Like many other plant lineages, polyploidy and reticulate evolution are important drivers of speciation in Isoetes. In the southeastern US Isoetes flora, polyploidy is common. We used a rapid DNA flow cytometry protocol to generate C values for four diploid, one tetraploid, and one hexaploid Isoetes species and conducted preliminary cytological investigations of two communities of Isoetes. Our work showed noteworthy variation in diploid Isoetes 1C values (1.39 to 3.32), including the smallest 1C value reported for the genus, Isoetes melanopoda ssp. silvatica. The hexaploid species, Isoetes microvela had the highest 1C value (4.21), and the tetraploid species evaluated had an intermediate 1C value (3.37). However, based on the variation in diploid 1C values measured...

The Burmanniaceae contain several lineages of achlorophyllous mycoheterotrophic plants that associate with arbuscular mycorrhizal fungi ( AMF ). Here we investigate the isotopic profile of a green and potentially mycoheterotrophic plant in situ , B urmannia coelestis , and associated reference plants. We generated δ ¹³ C and δ ¹⁵ N stable isotope profiles for five populations of B . coelestis . B urmannia coelestis was significantly enriched in ¹³ C relative to surrounding C ₃ reference plants and significantly depleted in ¹³ C relative to C ₄ reference plants. No significant differences were detected in ¹⁵ N enrichment between B . coelestis and reference plants. The isotopic profiles measured are suggestive of partial mycoheterotrophy in B . coelestis . Within the genus Burmannia transitions to full mycoheterotrophy have occurred numerous times, suggesting that some green B urmannia species are likely to be partially mycoheterotrophic but in many conditions this mode of nutrition may only be detectable using natural abundance stable isotopic methods, such as when associated with C ₄ mycorrhizal plants.

The root holoparasite, Hydnora esculenta is a poorly known perennial herb described from southwestern Madagascar. The key character in the original diagnosis was floral dimorphism, a hermaphroditic form and an apparently thinner and longer sterile form. Other useful diagnostic characters are lacking. The type specimens consist only of slices of fruit, and lack important diagnostic characters, thus, an epitype is designated here. The original description is amplified based on field collections and examination of available herbarium material. Flowers of H. esculenta are variable in size (11.6–26.9 cm long) and merosity (3–6), but are uniformly hermaphroditic like all other Hydnoraceae. Osmophores situated on tepal apices combined with angular rhizomes separate H. esculenta from other known Hydnora spp. Additionally, ribbed tepal margins for H. esculenta are diagnostic and are preserved on herbarium specimens. Pollination biology follows the general pattern for the genus, brood‐site mimicry with insect imprisonment and release. Floral mobbing events by the putative pollinator, a scavenger scarab beetle ( Kuijtenous laviceps ) are reported. The most common observed host of H. esculenta was the invasive tree Pithocellobium dulce . The range of H. esculenta maybe increasing due to the spread of P. dulce in riparian areas and disturbed habitats in southern Madagascar.