Quiabentia verticillata

Range, growth form and historical names

The species grows in eastern Bolivia, western Paraguay and northwestern Argentina. It reaches a larger size and has larger vegetative organs than Brazilian Q. zehntneri. Both species produce pink to purple flowers opening during the day. POWO synonyms include Q. chacoensis and Q. pflanzii. [Taylor et al. 2026] [2-WWW]

Leaves during increasing drought

Nobel and Hartsock studied plants identified as Q. chacoensis. After seven days of drought, total daily leaf CO₂ uptake fell by 71% and daytime uptake by 82%. Nocturnal uptake increased by 78% relative to its small initial value during this period. Day and night temperatures were 25/15°C under a twelve-hour photoperiod. [Nobel and Hartsock 1987]

The experiment table gives daytime and nocturnal values of 129 and 9 mmol CO₂ m⁻² respectively in hydrated plants, 24 and 16 after seven days of drought, and 0 and 2 after fourteen days. The initial increase in nocturnal assimilation was therefore a temporary component of the response to water deficit. Under more severe drought, both components of daily balance were restricted. [Nobel and Hartsock 1987, tab. 1, p. 116]

The green stem and carbon recovery

In the same experiment, the stem took up CO₂ during the day when well hydrated, while after seven days of drought its positive balance shifted to night. Martin and Wallace later showed that nocturnal acid increases in leaves and stems also include respiratory carbon. Retained leaves thus combine high daytime activity with the ability to change the metabolic rhythm. [Nobel and Hartsock 1987] [Martin and Wallace 2000]