Branch length mediates flower production and inflorescence architecture of Fouquieria splendens (ocotillo)

Abstract

The capacity of individual branches to store water and fix carbon can have profound effects on inflorescence size and architecture, thus on floral display, pollination, and fecundity. Mixed regression was used to investigate the relation between branch length, a proxy for plant resources, and floral display of Fouquieria splendens (ocotillo), a woody, candelabraform shrub of wide distribution in arid North America. Long branches produced three times as many flowers as short branches, regardless of overall plant size. Long branches also had more complex panicles with more cymes and cyme types than short branches; thus, branch length also influenced inflorescence architecture. Within panicles, increasing the number of cymes by one unit added about two flowers, whereas increasing the number of cyme types by one unit added about 21 flowers. Because flower production is mediated by branch length, and because most plants have branches of various lengths, the floral display of individual plants necessarily encompasses a wide range of inflorescence size and structure.

Ocotillo flowers as food resource for the mule deer during the dry season

“…The number of inflorescences per individual plant was 29.45 (± 8.23) and the number of inflorescences available at 1.8 m height was 12.24 (± 3.08) per plant. The availability of inflorescences Reyes-Carmona and García-Gil 1982;Bowers 2006) and, due to their tubular shape, are visited by insects and birds, in addition to being consumed by some birds (i. e., Icterus sp.) and mammals (i. e., Odocoileus hemionus).…”

“…It has no leaves for most of the year; these emerge suddenly after the first rain (March) (Zamudio 1995). Inflorescences are terminal (Reyes-Carmona and García-Gil 1982;Bowers 2006) and emerge simultaneously in all plants in early spring (March) and last a little more than a month. Some studies have determined that plant size is positively related with the number of inflorescences (Díaz et al 2015), although not necessarily with a larger number of flowers (Bowers 2006).…”

“…Inflorescences are terminal (Reyes-Carmona and García-Gil 1982;Bowers 2006) and emerge simultaneously in all plants in early spring (March) and last a little more than a month. Some studies have determined that plant size is positively related with the number of inflorescences (Díaz et al 2015), although not necessarily with a larger number of flowers (Bowers 2006). The bright red flowers are small (2.5 cm, diameter, 5) smallest diameter, 6) total number of inflorescences, and 7) number of inflorescences available for the deer (to a maximum height of 1.80 m, considering the height reached by an adult animal standing on its hind legs (see Figure 2).…”

Dry Mass Partitioning and Gas Exchange for Young Ocotillos (Fouquieria splendens) in the Sonoran Desert

“…Individual branches on juvenile plants elongate every year until they are >1 m tall, after which they typically bear flowers and only elongate every 2 to 3 yr (Darrow 1943;Bowers 2005Bowers , 2006. Thus, as acquired and stored stem resources, which are primarily in the cortex and wood (Henrickson 1969;Carlquist 2001), are allocated to reproduction in adult plants, it is likely that the overall rate of stem elongation is reduced and that the scaling exponents for plant height and number of basal branches versus total plant dry mass will be smaller for adults than for juveniles.…”

“…Seedling survival for ocotillos is low (Bowers et al 2004), and small plants are absent at some sites (Nobel and Zutta 2005), indicating that recruitment is uncommon. Once established, ocotillos usually do not flower until they have branches longer than 1 m, and branches produce larger and more complex inflorescences as they increase in length (Darrow 1943;Bowers 2005Bowers , 2006.…”