A foundation monograph of Ipomoea (Convolvulaceae) in the New World

Peduncles and pedicels
Peduncles may be short or long and the length is sometimes significant. Most species with a terminal inflorescence have very short peduncles and pedicels. However, some trailing or twining species are also remarkable for their relatively short peduncles. These include Ipomoea eriocalyx and a miscellaneous group of other species, such as I. lindenii, I. chapadensis, I. riparum and I. chrysocalyx but is most common in Clade A2. Species in this clade with very short peduncles include I. microdonta, I. lachnea and I. calophylla from the Caribbean, I. goyazensis from South America, I. isthmica and I. heterodoxa from Central America and I. pseudoracemosa, I. pruinosa, I. conzattii and I. tehuantepecensis from Mexico. Many of these species with short peduncles also have short pedicels so the whole axillary inflorescence is very compact. However, there is also a group of species with relatively long peduncles but a subcapitate inflorescence in which the flowers are borne on short pedicels. This is particularly characteristic of the Pharbitis Clade (I. indica, I. neurocephala, I. mairetii, I. lambii and I. villifera) but is also noteworthy amongst many unrelated species including I. racemosa, I. amazonica, I. argentinica, I. bahiensis, I. eriocalyx, I. fasciculata, I. exserta and I. batatas. Species with pedunculate subcapitate inflorescences often but not always have a bracteolate inflorescence. Very long peduncles are also distinctive in species such as I. marcellia, I. macdonaldii, I. longibarbis, and I. austrobrasiliensis. Unusually long pedicels are rarely apparent but are a feature of I. pedicellaris and its allies which include I. regnellii, I. lindenii and I. tentaculifera, these inflorescences appearing very lax. Unusual features of the peduncle include the winged peduncles of I. decemcornuta and I. kahloae, the peduncle fused with the petiole for some of its length (I. connata, I. dumosa, I. bracteata) and the peduncle that passes through the leaf sinus (I. aristolochiifolia, I. huayllae). Very occasionally pedicels are unusually slender and coiled (I. heptaphylla, I. tenera).