Ourisia Comm. ex Juss.
Fls in terminal verticillate bracteate panicles, sts much reduced. Calyx 5-lobed, some or all of clefts extending almost to base. Corolla weakly zygomorphic, with short slightly oblique tube ± hairy within, and 5 spreading lobes, the posterior two shortest and overlapping the lateral ones in bud. Stamens 4, didynamous, inserted near base of corolla-tube, staminode minute, anther-cells apically confluent. Style long, stigma capitate. Capsule ovoid-conical, loculicidal; seeds ∞, reticulate. Low-growing perennial herbs with opp. us. strongly veined lvs. Some 24 spp., about 12 in South America, 1 in Tasmania, the N.Z. spp. endemic.
SYNOPSIS
- A.
- Calyx equally divided, all clefts extending almost to base; floral bracts in whorls of several fls
- 1.
- Glandular hairs present, at least on pedicels; often some parts of plant glab.:
- 1. macrophylla
- 2.
- Glandular hairs absent; non-glandular hairs ¥ on most parts of plant:
- 2. colensoi, 3. crosbyi
- B.
- Calyx unequally divided, posterior clefts not extending to base
- 1.
- Plants predominantly glab.; no glandular hairs
- (a)
- Floral bracts in whorls; tufted plants with large lvs:
- 4. macrocarpa
- (b)
- Floral bracts in pairs; ± mat-forming plants with small lvs:
- 5. cockayniana, 6. caespitosa, 7. vulcanica, 8. modesta
- 2.
- Plant conspicuously hairy; glandular hairs ∞; floral bracts in pairs:
- 9. glandulosa, 10. sessilifolia
Key
The above description is based on N.Z. spp. Wettstein (Pflanzenfam. 4 (3b), 1895, 88) lists Ourisia in subfamily Rhinanthoideae where the two posterior corolla-lobes are covered in the bud by one or both of the lateral lobes. Cheeseman (Man. N.Z. Fl. 1925) follows Wettstein in his key but in the genus description says of the corolla-lobes "one of the lateral ones on the outside" in the bud. In all buds recently examined both the posterior corolla-lobes lie outside the laterals and this raises a question whether N.Z. plants are in fact congeneric with those of South America.
In N.Z. spp. the corolla is white, occ. with reddish flush outside, and us. with some yellow in the hairy part of the throat.
Chief difficulties in identification come from dwarfing under unfavourable conditions, accompanied by reduction and simplification of infl.; spp. us. represented by robust plants 30-40 cm. tall with ∞-fld infl. can sts appear as single-fld individuals barely 5 cm. tall. In such cases the form of calyx and kind and distribution of hairs us. together give reliable guides to affinities. Galls due to mites and other insect damage are apparently not uncommon and sts cause atypical local growths of hairs. Strongly papillose epidermal cells on some or all of the corolla-lobes have been seen on many herbarium specimens and are often associated with abnormalities in fl. or infl.
For comparison of specimens with types at K, especially regarding kinds and distribution of hairs, thanks are due to G. G. Pritchard.
Wettstein (loc. cit. 88) attributes 6 N.Z. spp. (mentioning by name macrophylla, macrocarpa, and caespitosa) to Section Dichroma (Endl. et Poepp.) Benth. with all calyx-lobes alike and corolla-tube straight; only the three spp. grouped under A in the synopsis above show consistently equal calyx-lobes. Section Euourisia Wettst. has the diagnosis: the three upper calyx-lobes con-crescent to the middle or higher, the calyx thus two-lipped; corolla-tube curved. Spp. grouped under B above have the posterior or upper calyx-lobes at least partly fused, though not always halfway and in O. macrocarpa var. calycina much less. No correlated differences in corolla-tube have been noted except in O. modesta.
