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XVII. Description of a new Genus qfP1mzts belonging to the Na tura l Family BignoniaceE. By DAVID DON, Esq., Libr. L.S., Prof. Bot . King's Coll. Lord.

* Read November 20th, 183s.

T H E interesting subject of the present paper formed part o f a small but valuable collection obtained during a journey through the interior of South- ern Africa to the western coast, by Captain Sir James Edward Alexander, who has recently given to the world the result of his observations on those hitherto little known regions, and who obligingly presented to me the specimen whence the accompanying drawing and description were taken, and which happened to be the only one of the plant he collected. I t was discovered by that enter- prising traveller, growing in dry arid soil, in the open desert, called the Great Flat or Kei Kaap, in Great Namaqua Land, in 25 S. latitude, and 17 E. lon- gitude. The plant was but just then in flower, so that the fruit even in an early state is still a desideratum. Sir Jatnes Alexander represents it as a thorny bush, about six feet high, with several straight, nearly simple, twiggy stems, bearing small hoary wrinkled leaves, and white flowers. Indeed the whole aspect of the plant bespeaks the aridity of the region in which it grows.

There can be no doubt that the plant does really belong to the BignoniaceE, although in habit it bears a stronger resemblance to JrerbenmeE, especially to Duran ta and Gnzelinn, and, in the absence of both flower and fruit, one would never suspect that the specimen pertained to a Bignoniaceous plant. In its spathaceous calyx, and in its regular funnel-shaped corolla, the genus comes near to Spathodea, but is abundantly distinguished from it by the cells of the anthers being parallel, and connate from the middle upwards. The ovarium I have only seen in a very young state, and I am therefore unable to say any- thing concerning the probable condition of the mature fruit or of the seeds. On the specimen are two fully expanded flowers Qnd a bud. The calyx in all

2 s 2

306 Prof. DON’S Description of a ww Genus of Plants

three has six teeth, and both the expanded flowers have a six-cleft limb ; one of these is furnished with seven stamens, and the other, as well as the bud, with six. The stamens are erect, nearly equal in length, and partly project beyond the tube of the corolla. The flowers are therefore completely regular, and, from the circumstance of the two expanded flowers and the bud having a six-lobed l imb to the corolla, and being furnished with six or sometimes even with seven stamens, we may justly conclude that the normal number is really six in this plant ; but had there been ody a single flower, I should have re- garded the excess of lobes and stamens as an accidental occurrence, and the normal number as five, as in those species of Spathodea which have the fifth stamen perfectly developed, and the flower consequently pentandrous.

The following are the characters of h a ne* ~~ :

C CTEs. Syst. Linn. H ~ W ~ R I A MONOQYNIA.

C B ~ . Br.

Cdyx spathac hinc ESSUB, inde 6dentatus. Corolla infundibuliformis : Stamina 6, rarb 7, subaequalia, exserta.

Ouarium abbre-

Folia fascicwlata, simplicia, penni-

limbo 6-lobo, patenti, Eequdi. Antherarurn loculi paralleli, e medio surshm connati. viatum, conicum, biloculitre ?

nervia, crenato-serrata. Frutex (namaquensis) erectus, spinosus.

Flores laterales, subsessiles, speciosi, albi,

Descriptio.

Frutex erectus, rigidus, spinosus, orgyalis, basi multidivisus. .

Caules plures, virgati, siinpliciusculi, obsoletk tetragoni, cortice spadiceo, pube stellat% brevissim8, prEsertim apicem versus, densk canescenti-tomentosi. Spinae (gemme prirnariae mutat%) supra-axillares, decussato-opposi t z , subu- latae, validae, horizontaliter porrectae, vix pollicares. Folia primarin non- dhm vidi ; secundaria in ramulis parbm evolutis fasciculata, simplicia, pe- tiolata, ovalia v. cuneata, retusa, levitkrque emarginata, gross& aequalitkr- que crenato-serrata, coriacea, semipollicaria, penninervia, subtiis costata,

belonging to the Natural Family Bignoniaceae. 307

sup& transversh subplicata, pube stellatil utrinque dens& tomentosa, in- cana. Petioli brevissimi, teretiusculi, tomentosi, inarticulati. Flores in ramulis foliiferis laterales, pauci (3), subsessiles, speciosi. Pedunculi bye- vissimi, crassi, teretes, densk tomentosi, vix sesyuilineam longi. CnZyx tubulosus, spathaceus, inembranaceus, subths tertiil parte fissus, parhn ventricosus, undique pilis ramosis albidis copiosissimi: vesti tus, apice 6- dentatas : dentibus subulatis, erectis, brevibus, lanatis. Corolla ampla, alba, regularis, infundibuliformis : titbo calyce subduplb longiore, basi inths villoso, surshm dilatato : limbo 6-ficlo, patenti : lobis cuneato-rotun- datis, subaequalibus, integris, venosissianis, margine paululhm incurvis, undulatis et subrepandis, mtivatione iinbricatis. S'tnnzirza 6 , rarb 7, erecta, subaequalia : filanzentu compressa, glabra, cor01l;e tub0 infrd ad- hErentia, in]% basi barbata : anther@ exsertae, incumbentes, biloculares, utrinqiie obtusae, apice subrecurvatae : loculis longis, parallelis, & medio surshm connectivo prominenti connatis, sutut.2 longitudinali dehiscenti- bus. Ouariunz abbreviatum, conicum, compressum, villosissimum, bilocu- lare ? basi annulo carnoso integerrimo cinctum. Stylus tenuis, compres- sus, glaber, vix staminum longitudine. Stigma bilaniellatum : Zaciniis subrotundo-ovatis, planis, dilatatis, superficie margineque minutissitni: papillosis. Fructus mihi ignotus.

Species unica. C . Alesandri. TAB. XXII. Crescit spontk in Africae Australis Terrae Namaquensis deserto rnagno Kei

F1. Martio. J. E.

The most remarkable characters of this plant, and which separate it from all other known genera of Bigtzoniacece, consist in its regular symmetrical flowers, having an unusual number both of divisions and stamens. In the form of its calyx and corolla it agrees, as we have already stated, with Spa- thodea, and in the parallel cells of its anthers and exserted stamens, with Mil- Zingtonia. From the shortness of the ovarium, we suspect that, a considerable difference will be presented by the mature fruit from the rest of its coordi- nates. The habit, as already noticed, is altogether that of Verbenucea?.

From the position which the Bigmliiacece occupy in the series of natural

Kaap v. Great Flat a Cblonis dicto, lat. 25 . long. 17. Alexander, E p . Aur. 5. (v. s. sp. sine fructu.)

308 Prof. DON'S Description of a npw Genus of Plants.

affinities, and connected, as they are, on the one hand with the symmetrical families Cobceacee, Polemoniacee, and even Apocynece, arid on the other with the unsymmetrical ones of Cyrtundracece, Acunthacee, Pedalinee, Sesumee, and Scrophularinece, we need not be surprised to find amongst them genera with perfectly symmetrical flowers.

The generic name refers to the peculiar situation of the leaves and flowers below the spines, and is compounded of xhrw, inzra, and ppaxro's, munitus. Its enterprising discoverer is cornmemorated in the specific name.

EXPLANATION O F TAB. XXII.

Fig. 1. IJpper portion of a stem of Catopkractes Alexandri. Fig. 2. Tube of the corolla laid open, with the stamens. Fig. 3. Pistillum ; all of the natural size.

Note.-Since the preceding account was read before the Society, I have been favoured by Mr. Burchell with flowering specimens of two species of his remarkable genus Rhigoxum, namely R. spinosum and obovatum, and by Mr. Bentham with a specimen of the latter species, with two separate fruit. These plants agree well with the present in habit, but the calyx is short, wide, and campanulate, with an equal limb, neither cloven, nor spathaceous ; the corolla has a very short tube, much narrower than the calyx, with the faux much di- lated, ventricose, and campanulate ; the stamens are unequal in length, two of them being longer than the rest. The margin of the leaves in all the spe- cies of Rhigoxum hitherto known is perfectly entire. From these differences, therefore, it is evident that Catophractes must either constitute a distinct ge- nus, or a very marked section if united to Rhigoaum. It clearly forms the transition from that genus to the pentandrous simple-leaved Spathodece.