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A revision of Philodendron subgenus Meconostigma (Araceae)

Observations of gynoecial structure in Philodendron (Araceae)

The chromosome numbers of 75 species belonging to the family Araceae have been determined. The numbers for 53 species are reported for the first time. One number differs from previous reports (Aglaodorum), and one number is corrected (Phymatarum). Within 15 genera (Gymnostachys, Pothoidium, Alloschemone, Heteropsis, Holochlamys, Anaphyllopsis, Dracontioides, Pseudohydrosme, Montrichardia, Bucephalandra, Taccarum, Asterostigma, Gorgonidium, Spathantheum and Ulearum) the chromosome numbers have not previously been determined. The total number of genera cytologically investigated is now 99 (c. 94%).



A great diversity in chromosome numbers as well as in chromosome size and constitution is found. The results are discussed in relation to the phylogeny and the previously published classifications of the family.



A total list of chromosome numbers counted (>700 species) in the Araceae is presented (Appendix).

Cytology and systematica of Araceae

Survey of shoot organization in the araceae

History and current status of systematic research with Araceae

Vascular patterns in stems of Araceae: subfamilies Colocasioideae, Aroideae and Pistioideae

A survey of 480 eolleetions of stem material of Philodendron has established five patterns of vascular organization. Species representing eaeh of these patterns were analyzed by cinematographic methods to allow a three-dimensional interpretation of the course of vascular bundles over extended distances. Pattern 1 has mainly collateral organization, but with some bipolar bundles. Pattern 2 has a majority of central bundles aggregated into compound (multipolar) bundles; Pattern 3 differs in that almost all bundles of the eentral cylinder are multipolar. Patterns 4 and 5 inelude eompound vaseular bundles in which the individual strands are not very diserete so that in Pattern 5, whieh is the most eommon in the genus, the bundles might be described as amphivasal. In Section Pteromischum, which has monopodial construetion, the majority of speeies exhibit Pattern 2 which is exelusive to this group. Other correlations with subgenerie groupings are emphasized. OUR RECENT general survey of vascular systems in the Araceae (French and Tomlinson, 1980, 1981a cl, 1983) suggested the need for a more detailed follow-up study of the large genus Philodendron because of its morphological diversity, with preliminary indication of comparable diversity in vascular organization. Here we examine stem vasculature of Philodendron at two levels: 1 ) a general screening of vascular anatomy in single transverse sections from stems of as many species and collections as possible (480 total collections, partly indicated in Table 1); 2) a more detailed three-dimen

J. C. French

Papers

Vascular patterns in stems of Araceae: subfamilies Colocasioideae, Aroideae and Pistioideae

Patterns of stem vasculature in philodendron