Induction of Flowering in Echinodorus Species
Vegetative propagation in small species usually occurs through cuttings on runners; in larger species juvenile plants occasionally develop on rhizomes. Most productive, though, is reproduction through adventitious plants which, in many Echinodorus, are formed on the whorls of the inflorescences. These will
also appear occasionally in aquariums, which is always an indication of good growth. If the inflorescence strives to protrude from the water, it should be pressed back under water to enable better development of adventitious plants. As soon as the adventitious plants are strong enough and have formed roots, they can be removed by slightly twisting them and subsequently be planted. The flowers will not normally open under water. The study of the flowers thus necessitates the protrusion of the inflorescence from the water.
Triggering factors for the formation of flowers can be temperature and the length of the lighting period. During cultivation it was found that some Echinodorus species, independent from the light situation, will only flower in summer, others only in winter, and others during the entire year, thereby developing their individual and specific growth formations. Accordingly, one distinguishes between short-day plants (plants which flower
- The flowers of Echinodorus are often visited by butterflies.
during a lighting period of less than 12 hours), long-day plants (flower formation occurring during a daylight period of more than 12 hours), and day-neutral plants (daylight period has no influence on the formation of flowers). This photoperiodic behavior can, for example, be utilized in plant nurseries in order to increase reproductive productivity. In some species, inflorescences with adventitious plants may be induced early on in very small plants with the aid of the lighting period, while other species require a cold period prior to flowering.
Published observations and opinions on the flower induction of individual species will not always tally. The credibility of the authors, however, is not in question. Rather, variations in flowering behavior can be explained by the geographic origin of the plants. It might well be that populations from countries with a large geographic distance in their north-south direction have adapted to the different native conditions in their habitats and thus react differently to the length of the lighting period. For example, Echinodorus berteroi is considered to be a long-day plant, van der Vlugt (1993b), however, reports— entirely credibly—that his specimens imported from Curaçao have proven to be day-neutral.
Previous observations on the induction of flowering in Echinodorus species are in no way complete. They are rather fragmentary, but could be further expanded in cooperation with aquatic plant nurseries as well as studies in native habitats. There exists a wide scope for experimentation for those interested in this topic!
Insofar as the flowering behavior of individual Echinodorus species is well known and can be confirmed by the author, it has been included in the plant catalogue.
Infructescence of Echinodorus schlueteri.
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