| Full text | |
| Author(s): |
De-Paula, Orlando Cavalari
[1]
;
Sajo, Maria das Gracas
[1]
;
Prenner, Gerhard
[2]
;
Cordeiro, Ines
[3]
;
Rudall, Paula J.
[2]
Total Authors: 5
|
| Affiliation: | [1] Univ Estadual Paulista UNESP, BR-13506900 Sao Paulo - Brazil
[2] Royal Bot Gardens, Richmond TW9 3DS, Surrey - England
[3] Inst Bot, BR-04301012 Sao Paulo - Brazil
Total Affiliations: 3
|
| Document type: | Journal article |
| Source: | PLANT SYSTEMATICS AND EVOLUTION; v. 292, n. 1-2, p. 1-14, MAR 2011. |
| Web of Science Citations: | 16 |
| Abstract | |
New observations are presented on the ontogeny, vasculature and morphology of both staminate and pistillate flowers of Croton and Astraea. These data support earlier hypotheses that the filamentous structures in pistillate flowers represent reduced and transformed petals. Staminate flowers of both genera possess five free nectaries, which are vascularisal by divergences of the sepal traces in Croton and unvascularised in Astraea. In pistillate flowers, there are five separate non-vascularised nectaries in Astraea, but in Croton there is a single nectariferous disk that is vascularised by divergences of the sepal traces. The nectaries are initiated late in floral development, but their location indicates that they could represent the outer stamen whorl transformed into secretory staminodes. Other glandular structures occur in pistillate flowers of most Croton species, resulting in flowers with two secretory organ whorls. In these cases, the inner whorl is formed by modified staminodes. Our observations support the recent segregation of Astraea species from the larger genus Crown. Despite strong similarities between the two genera, there are clear structural differences, including the presence of colleters in Astraea (absent in Crown), moniliform trichomes on petals (rather than simple trichomes in Crown), non-vascularised nectaries (vascularised in Croton) and reduced, non-secretory filamentous structures (well developed and secretory in Croton). (AU) | |