Timing of Berberis Infructescence in Hays County

In 2004 the development of fruit of B. trifoliolata (BETR), B. swaseyi (BESW) and hybrid (BESxT) bushes was recorded twice a week from the end of April to the end of June. The latest a BESW bush had berries was June 29. The sampling continued the plant sample begun in mid February, as modified: BETR, 23 to 27 bushes; BESW, 25-26 bushes; BESxT, 7 bushes. In 2005 and 2006 a similar survey was conducted with those plants of the extended survey set that had bloomed and which had produced at least one ripe fruit. The number of hybrids with blooms had grown to 13 in 2005, to 17 in 2006.

In 2004 nearly all blooming plants produced abundant ripe fruits, providing a solid database for all aspects of maturation phenology. 2005, by contrast, was marked by extremely few fruits. A high percentage of plants having bloomed produced no ripe fruits; and of those that did produce fruit, most had only a few berries that fully matured. Unlike 2004, there was no basis for plotting periods of peak infructescence in 2005. In 2005 the paucity of fruit seemed to result from fungal infestation and an abundance of insect damage, especially from larvae of unknown origin, during the bloom cycle. In 2006, the winter—spring drought severely impacted the development of fruit for B. trifoliolata, and only two plants, adjacent to springs, had more than just a few fruits. [The 2006 survey is still ongoing.]

Survey Plants that Bloomed in 2005 and Produced Green Fruits

	n for Bloom Survey	Plants with Green Fruit on April 30	Percent
BETR	30	17	57%
BESxT	13	6	46%
BESW	20	13	65%

Chart 1 shows the percentages of plants of each set that had at least one ripe fruit at the given date in 2004 & 2005. The results for the two years are essentially the same — considering the lack of fruits in 2005, with the hybrids intermediate, as with the bloom times.

Chart 1

Chart 2 shows periods of peak fructescence in 2004 - the point at which a bush was judged to be uniformly covered with red (ripe) fruits or, in the case of a few plants with relatively few fruits, the point at which the number of ripe fruits began to decline. For some bushes the peak stage extended over several dates.

Chart 2

Observations

As with blooming the hybrid set had infructescence times that were intermediate between those of the two species.
There was almost a 3-week period of overlap in overall infructescence for BETR and BESW in 2004 — three times as long as the overlap in blooming.
There was no overlap in 2005 or 2006. I interprest this as partly a reflection of the paucity of fruits in 2005 and the drought-curtailed blooming period for B. trifoliolata in 2006.
The period of fructescence for the hybrid set was relatively more distinct than its bloom time (which was judged to be closer to that of BETR), perhaps because the larger berries take longer to mature.