Identification of the Developmental Phases in Poinsettia

Abstract

<jats:p>Experiments were conducted with poinsettia <jats:italic>[Euphorbia pulcherrima</jats:italic> (Willd. ex. Klotzsch)] to determine the 1) existence of developmental phases from seedling establishment to flower induction and 2) characteristics that may be used to delineate the phases. The characteristics evaluated were flowering and rooting ability, heterophylly and other leaf characteristics, phyllotaxy, and internode characteristics. Two developmental phases, juvenility and maturity, were identified. The transition between these phases occurred in poinsettias that were 6 to 8 weeks old, following establishment. Mean values for flowering ability, rooting ability, phyllotaxy, and heterophylly differed for the two developmental phases, rendering them the most useful of the characteristics evaluated for identifying developmental phases in poinsettia.</jats:p>

Meristem Ontogenetic Age as the Controlling Factor in Long-day Floral Initiation in Poinsettia

“…The chemical signals required for floral initiation may be present under LD, but the meristem may not be competent to respond to these signals until after a specific ontogenetic age has been achieved. That this may be the case in poinsettia is supported by Siraj-Ali et al (1990b) who found that poinsettia plants produced from seed vary in their competence to respond to SD depending on age. Further, in Citrus sinensis (L.) Osbeck (Furr et al, 1947), Larix leptulepsis L.…”

Number of Stock Plant Shoot Nodes Influences Splitting of `Lilo' Poinsettia

“…Poinsettias exhibit distinguishable physiological or developmental phases. As the vegetative stem grows and elongates, the terminal, though the youngest portion of the stem, becomes progressively more mature in character (Poethig, 1990;Siraj-Ali et al, 1990a). Many workers, including Seeley (1988) and Larson (1990), have observed that as poinsettia stems elongate, they become more prone to splitting.…”