Cattail regrowth in Madrid
New cattail shoots have arisen from submerged plant organs (collar and rhizomes) of Green Floating Filters (GFF) of the Technical University of Madrid (UPM) since the last week of February (Figure 1A & 1B). With the arrival of the good weather the dormant period of cattails is ended and sprouting begins. Thus, mean temperature rose from 5.0ºC in January to 9.1ºC in February; temperatures have become milder in March. Minimum temperature for cattail growth has been reported about 10ºC. Ending January temperatures increased to 11.5ºC mean value for 7 days, from 28/01 to 3/02. Then, they went down and afterwards up. Temperatures above 10ºC were recorded on 12/02 and 13/02 and from 23/02 to 5/03 (Figure 2). The last frost observed was observed on 20/02 (Figure 3). No damages by low temperatures have been noticed so far.
