Development and Distribution of Mucilage Canals in Lycopodium

Abstract

Two distinct types of mucilage canals are found in Lycopodium. One type, the veinal canal, is found in both sporophylls and in vegetative leaves, and is always in close proximity to the leaf trace. The other, the basal canal, is restricted to the strobilus where it forms a complex and extensive mucilaginous cylinder in the outer cortex and extends into the base of the sporophylls. Protruding secretory cells are formed in both types during a lysigenous developmental process. The occurrence of these two types of canals correlates with the three subgenera. Urostachys which lacks canals, Lepidotis which possesses both veinal and basal canals, and Lycopodium which possesses only basal canals.

Diversification and Relationships of Extant Homosporous Lycopods

“…Another well supported grouping is the Pseudodiphasium [Lycopodium volubile G. Forster) -Magellanica clade. Even though there are few similarities in habit between L. volubile and section Magellanica, features of spore morphology (Wilce, 1972] and the absence of basal mucilage canals in their sporophylls (Bruce, 1976b;011gaard, 1987) support this grouping. In Lycopodium, two more subgeneric group relationships are supported.…”

“…One factor contributing to the inflation of subgeneric groups is the segregation of several divergent m mor imilar to find similarities between such groups. Works looking at various morphological features such as stem anatomy (Bierhorst, 1971;Jones, 1905;Ogura, 1972), spore morphology (Tryon and Lugardon, 1991;Wilce, 1972), distribution of mucilage canals in trophophylls and sporophylls (Bruce, 1976b), (W,…”

“…The results are also somewhat surprising, considering morphological features. Section Caroliniana for example has several features, including isovalvate sporangia (011gaard, 1987) and absence of leaf veinal mucilage canals (Bruce, 1976b], that are best explained as retained plesiomorphic conditions. This would suggest a basal split in Lycopodiella separating section Caroliniana from remaining species, but such a relationship is not supported by molecular data (Wikstrom and Kenrick, 2000b].…”

New and existing combinations in Palaeotropical Phlegmariurus (Lycopodiaceae) and lectotypification of the type species Phlegmariurus phlegmaria (L.) T.Sen & U.Sen

“…Early classifications of this family usually included all of the species, irrespective of their shoot-form, together in the large and polymorphic genus Lycopodium L. One exception was the small and morphologically divergent Australian and New Zealand pygmy-clubmoss Phylloglossum drummondii Kunzewhich was historically placed in a genus of its own. Multiple genera and subfamilies corresponding with the different shoot-forms, gametophyte and spore types were recognised following multi-character systematic studies on the family (Bruce 1976, Holub 1964, Øllgaard 1975, 1979, 1987, 1989a, Wagner and Beitel 1992, Wilce 1972). Until recently, the most widely adopted of these classifications was the four-genus classification of Øllgaard (1987) which recognised Lycopodium L., Lycopodiella Holub, Huperzia Bernh.and Phylloglossum Kunze and was supported by a comprehensive nomenclatural index (Øllgaard 1989a).…”

Gametophyte of Lycopodium Digitatum

“…A taxon with an unusual combination of features that precluded its insertion in the above is L. volubile. It is an unusual plant sporophytically, not only with dichotomously pendant strobili reminiscent of epiphytic lycopods (Holloway, 1919), but also lacking the mucilage canals typical of its subgenus (Bruce, 1976). Its spores are also distinct (Wilce, 1972) although definitely related to the type of spores seen in L. clavatum and L. complanatum.…”