Sairocarpus

Herbs, annual, biennial, or perennial. Stems erect [ascending or sprawling], filiform, twining branches often present, glabrous, hairy, or glandular-hairy. Leaves cauline, sometimes basal, opposite or alternate proximally, alternate distally; petiole present or absent; blade linear to oblanceolate, not fleshy, not leathery, margins entire. Inflorescences terminal or axillary, racemes or flowers solitary; bracts present or absent. Pedicels 1–25(–30) mm; bracteoles absent. Flowers bisexual, cleistogamous or chasmogamous; sepals 5, basally connate, calyx bilaterally symmetric, tubular or cupulate, lobes ovate to lanceolate, shorter or as long as corolla tube in flower, adaxial largest, glabrous or hairy to glandular-hairy; corolla white to purple, pink, red, or tan, bilaterally symmetric, bilabiate and personate, tubular, 5.5–18 mm, tube base usually gibbous, not spurred (not gibbous, spurred in S. cornutus), lobes 5, abaxial 3, adaxial 2; stamens 4, basally adnate to corolla, didynamous, filaments glabrous or glandular-hairy, pollen sacs 2 per filament; staminode 0; ovary 2-locular, placentation axile; stigma punctiform. Fruits capsules, 2.5–11 mm, locules unequal, dehiscence poricidal. Seeds 5–40, brown to black, ovoid to oblong, wings absent. x = 8.

Distribution

w United States, n Mexico.

Discussion

Species 12 (9 in the flora).

Sairocarpus is sometimes treated as a subgenus of Antirrhinum (D. M. Thompson 1988; M. Wetherwax and Thompson 2012). For a discussion of the generic segregates, see 2. Antirrhinum.

Sairocarpus is a New World genus distinguished from the Old World Antirrhinum by its smaller flowers, disjunct distribution, and base chromosome number x = 8 following R. K. Oyama and D. A. Baum (2004) and P. Vargas et al. (2004). Additional study of generic limits may be warranted since more complete ITS sampling, including all Sairocarpus species in the flora area (M. Fernández-Mazuecos et al. 2013), revealed that Sairocarpus is polyphyletic if Gambelia, Howelliella, Mohavea, and Neogaerrhinum are recognized. Other New World-only segregates of Antirrhinum are Gambelia, Howelliella, Mohavea, Neogaerrhinum, and Pseudorontium; they can be distinguished from Sairocarpus by their fruits with equal locules. Plants of Mohavea and Pseudorontium also have distinctive, winged seeds.

Some species of Sairocarpus have filiform, twining branches, usually on the distal parts of the stems. These branches wrap around nearby objects giving additional support to these weak-stemmed plants.

Cleistogamous and chasmogamous flowers are produced in some species of Sairocarpus. The cleistogamous flowers usually form early in the season and are smaller and paler than the chasmogamous flowers. In species with twining branches, cleistogamous flowers are usually borne close to the main stem. Fruits from cleistogamous flowers are usually smaller and have fewer seeds than those from chasmogamous flowers. Only chasmogamous flowers are described below.

Selected References

None.

Lower Taxa

Sairocarpus cornutus, Sairocarpus coulterianus, Sairocarpus kingii, Sairocarpus multiflorus, Sairocarpus nuttallianus, Sairocarpus subcordatus, Sairocarpus vexillocalyculatus, Sairocarpus virga, Sairocarpus watsonii

Key

1	Calyx lobes unequal.	> 2
2	Stems viscid; branches not twining; plants annuals or perennials; corollas pale pink to red.	Sairocarpus multiflorus
2	Stems not viscid; branches twining; plants annuals; corollas white to tan or light purple.	> 3
3	Corollas 5.5–7 mm; leaf blades elliptic to linear.	Sairocarpus kingii
3	Corollas 8–17 mm; leaf blades ovate to narrowly elliptic.	> 4
4	Corollas white to tan, not veined; stems hairy.	Sairocarpus subcordatus
4	Corollas light purple to white, often dark-veined; stems glabrous or glandular-hairy.	Sairocarpus vexillocalyculatus
1	Calyx lobes equal to subequal.	> 5
5	Stems glandular-hairy.	> 6
6	Leaf blades linear to oblanceolate; stems self-supporting; branches not twining; capsules: abaxial locules indehiscent or with 1 pore.	Sairocarpus cornutus
6	Leaf blades ovate; stems not self-supporting; branches twining; capsules: abaxial locules with 1 pore.	Sairocarpus nuttallianus
5	Stems glabrous, or basally hairy and otherwise glabrous.	> 7
7	Branches not twining; capsules: abaxial locules with 2 pores; plants perennials; corollas pink to pale pink.	Sairocarpus virga
7	Branches twining; capsules: abaxial locules indehiscent or with 1 pore; plants annuals; corollas white to light purple.	> 8
8	Inflorescences racemes; pedicels 1–5 mm; corolla palates purple-spotted.	Sairocarpus coulterianus
8	Inflorescences flowers solitary; pedicels 4–25(–30) mm; corolla palates purple-veined.	Sairocarpus watsonii