A phylogeny inferred from large-subunit (26S) ribosomal DNA sequences suggests that Burmanniales are polyphyletic

According to several authors, the Burmanniales are an order that includes the families Burmanniaceae, Thismiaceae and Corsiaceae. At present, there is no consensus concerning the circumscription of Burmanniales. All members of Thismiaceae and Corsiaceae are mycoheterotrophic; Burmanniaceae are composed of both mycoheterotrophic and autotrophic species. Other than mycoheterotrophy, there are few characters that unite members of the order. Because mycoheterotrophy has resulted in extreme vegetative reduction that may have contributed to homoplasy in the form of character convergence, the systematics of Burmanniales is problematic. A phylogeny inferred from large-subunit (26S) ribosome-DNA sequences suggests that the order Burmanniales is polyphyletic. Specifically, the Burmanniaceae appears as strongly supported monophyletic group with Thismia as sister. Corsia is distinct and may be associated with the Liliales.