环境因素对短命植物抱茎独行菜抽薹开花节律的影响

以新疆十字花科典型早春短命植物抱茎独行菜(Lepidium perfoliatum L.)为材料,分别在不同环境、不同土壤基质及不同春化时间下栽培,以探讨环境因素对抱茎独行菜抽薹开花的影响。结果表明:抱茎独行菜种子在蛭石∶珍珠岩(3∶1)中的出苗率显著高于营养土和自然生境土壤,基质对抱茎独行菜植株是否抽薹无显著影响,但影响其抽薹的早晚及结实特性;人工4℃春化对3种不同栽培环境中于阳台生长植株的抽薹有明显促进作用,而对培养室及户外环境中栽培植株是否抽薹无显著影响;抱茎独行菜抽薹开花对光照和温度的响应最明显,光照时间由短变长与苗期一定时间的低温之间的相互作用是促使抱茎独行菜抽薹开花的关键因素。     

两种独行菜种子萌发生理特性研究

以两种在新疆具有代表性的十字花科独行菜属早春短命植物抱茎独行菜（Lepidium perfoliatum Linnaeus）和独行菜（Lepi-dium apetalum Willd）为材料,研究（光照、温度、外源激素ABA处理）对其种子萌发的影响。结果：两种独行菜种子萌发对光照不敏感;抱茎独行菜种子萌发的温度范围广,在0℃～25℃之间都可萌发,而独行菜种子则在低温下（0℃、4℃）不萌发,其萌发温度范围为10℃～25℃。两种独行菜种子对低温胁迫表现出不同的耐受性;0℃、4℃下,在培养基中加入不同浓度的ABA,对抱茎独行菜种子萌发有抑制作用。     

短命植物独行菜种子萌发过程对低温的耐受特性

以独行菜（Lepidium apetalum）为材料,研究了其种子在萌发过程中耐受低温的特性,并对耐受低温的机制作了初步的探讨。结果表明：1.萌发至I、II、III期的独行菜种子经过冷诱导处理后,对零下低温-5℃、-10℃胁迫具有较强的耐受性,这种耐受性随萌发发展相对有所降低。2.独行菜种子萌发过程中胚根生长速度明显受到低温抑制,但也仍然能够生长。3.适当时间的低温层积能使独行菜萌发势显著提高,对终萌发率影响不大;过长时间的低温层积会使独行菜种子萌发势和最终萌发率降低。4.独行菜种子在4℃条件下不能萌发,但4℃层积2d的种子经25℃处理6h以上后,可耐受4℃低温而萌发,且萌发率随25℃处理时间增加而升高。如果25℃处理时间少于5h则不能在4℃低温下萌发。经4℃层积10d、再经25℃萌发处理1h的独行菜种子就能在4℃低温下萌发。综合分析认为独行菜种子不能耐受4℃低温萌发,原因可能是在露白前存在一个关键的生理阶段,在4℃胁迫逆境中不能越过这个阶段,该阶段之前与之后的萌发过程都能耐受4℃低温,因此对低温胁迫有良好的耐受性。这为探索早春短命植物耐受低温萌发的机制提供了新的思路。     

土著菌根真菌和混生植物对羊草生长和磷营养的影响

植物种间相互作用直接影响植物生长、根系可塑性及养分吸收,而与植物共生的丛枝菌根真菌可以改变植物个体和种间养分资源的分配,具有协调种间竞争的潜力.以我国北方草甸草原建群种羊草(Leymus chinensis)和混生植物紫花苜蓿(Medicago sativa)及独行菜(Lepidium spetalum)为供试植物,通过模拟盆栽试验,研究了土著菌根真菌和混生植物对羊草生长、根系形态及磷营养的影响.试验结果表明,土著菌根真菌能够与羊草及紫花苜蓿形成良好共生,而独行菜根内基本未形成菌根共生结构.土著菌根真菌显著降低了羊草及独行菜的生物量,但促进了紫花苜蓿的生长;混种紫花苜蓿显著促进了羊草的生长,而混种独行菜则显著抑制了羊草的生长.土著菌根真菌对羊草根系形态的影响表现出与植株生物量类似的趋势,但不同混生植物对羊草根系生长均无显著影响.土著菌根真菌和混生植物对羊草植株磷含量均无显著影响.与混生植物相比,羊草具有较高的比根长和磷吸收能力,这也解释了其负向菌根依赖性.研究证实了菌根真菌和植物种间相互作用均是影响草原优势植物生长和根系发育的重要因素,深入研究其交互作用对于科学管理草地生态系统,维持植物群落的稳定性和生态系统生产力具有重要意义.     

山东堇菜属（堇菜科）植物叶表皮微形态的比较研究

利用光学显微镜对山东堇菜属Viola L.20种2变种植物的叶上、下表皮微形态进行了研究。结果表明,该属植物叶表皮细胞为多边形或不规则形,垂周壁为波形、浅波形或平直弓形,气孔器为不等型（偶上表皮兼有平列型）。根据其上表皮是否具有平列型气孔器,可将其分为两个类型,即①上表皮有平列型气孔器,如三色堇;②上表皮无平列型气孔器,如该属绝大多数植物。类型②又根据叶表皮细胞形状和垂周壁式样之不同,进一步划分为4个亚类型。表皮细胞形状和垂周壁式样对该属内种、变种的鉴定具有重要的意义。不赞成将早开堇菜、茜堇菜合并到紫花地丁;不支持将阴地堇菜作为蒙古堇菜的鉴定;不支持将泰山堇菜合并到早开堇菜、将总裂叶堇菜降为裂叶堇菜的变种。     

不同生长阶段苘麻生物量分配对种群密度和土壤水分的响应

通过研究不同生长阶段下植物生物量分配对土壤水分和种群密度的响应,揭示植物同时应对生物与非生物环境因子的策略。本研究在田间条件下对1年生草本植物苘麻（Abutilon theophrasti）进行加水和对照2种水分处理,每种处理下进行低、中、高3种种植密度处理,分别在生长20、50 d时测量植物根、茎、叶片、叶柄和繁殖（花和果实）生物量,探讨在不同生长阶段苘麻生物量分配如何响应于密度和水分。结果表明：植物生长20 d时,在加水处理中,与低密度相比,中密度提高了根生物量比率19.4%和根冠比21.5%,降低了叶生物量比率34.4%;未加水处理（对照）中生物量分配对密度的响应不显著;50 d时,对照处理下,高密度相对于低密度降低了总生物量63.5%,2种水分处理下高密度都降低了根冠比和根生物量比率,提高了茎生物量比率,不影响总生物量和其他器官生物量分配。结果说明施加水分前期更容易促进根生物量分配对密度的积极响应（增大）,后期减缓高密度对总生物量的不利影响（降低）。生物量分配对密度的响应取决于种内相互作用的强度,早期适中水平的相互作用更容易产生地下促进作用,促进根部的积极响应。中密度下适中的种内相互作用也可以促进根生物量分配和总生物量对水分增加的积极响应。生长阶段可以通过影响植物个体大小而改变植物相互作用强度,进而改变生物量分配对密度和水分可用性的响应。     

丛枝菌根根外菌丝网络形成过程中的时间效应及植物介导作用

以豆科植物紫花苜蓿为试验材料,应用三室(供体室-间隔室-受体室)培养系统,研究在供体和受体紫花苜蓿根系之间菌丝网络形成的时间效应以及间隔室中不同植物对菌丝网络建成的介导作用.第一个试验在供体和受体植物生长8、10、12、14周之后进行收获以检验菌丝网络形成的时间效应;第二个试验则在间隔室分别种植紫花苜蓿、羊草和独行菜,以考察菌根依赖性不同的植物对菌丝网络形成的介导作用.试验结果显示:(1)接种丛枝菌根真菌的供体紫花苜蓿根系能够形成良好的菌根共生,其外延菌丝可穿过尼龙网和间隔室侵染受体植物根系;植物生长8周后,在受体植物根系检测到菌根侵染,证实供体和受体植物间形成了根间菌丝网络;10周后,尽管供体室和受体室植物的侵染率已无差异,但二者的生物量和地上部磷浓度差异却加大,表现出菌丝网络对植物种内竞争影响的不对称性.(2)试验条件下,不同介导植物对受体植物的菌根侵染及生物量均无明显影响,但显著降低了供体植物生物量和地上部磷浓度;间隔室无介导植物或种植独行菜时,受体植物地上部和根系生物量显著低于供体植物,而当介导植物为紫花苜蓿和羊草时,受体和供体植物生物量无显著差异.研究表明,植物根间菌丝网络的形成受时间和介导植物的影响,同时也具有调节植物间资源分配和植物相互作用的功能.     

中国独行菜族部分属种的叶表皮观察

利用光学显微镜对中国十字花科独行菜族部分广布属及相关属植物进行了叶表皮微形态学观察研究,结果表明:所研究的中国独行菜族植物叶表皮微形态具有多样性,可以划分为两种类型:第一类,叶上下表皮同形或近同形,叶表面被单毛或光滑无毛,包括独行菜属、群心菜属、菘蓝属和菥蓂属;第二类,叶上下表皮不同形,叶表面被分支毛和单毛,包括荠属和亚麻荠属;叶表皮微形态结果支持荠属应从独行菜族中移出,独行菜族是一多系类群,同时认为荠属与亚麻荠属植物具有较近的亲缘关系。     

抱茎独行菜种皮粘液质相关基因TTG1的克隆、表达分析及功能鉴定

抱茎独行菜（Lepidium perfoliatum L.）为十字花科具典型粘液质繁殖体植物,而TTG1基因（Transpa-rent testa glabra 1）所编码的蛋白是调控种皮细胞分化并影响粘液质释放的转录因子。目前关于TTG1基因在粘液质繁殖体植物中的研究报道较少,为探究TTG1基因在抱茎独行菜粘液质发育中的作用,本研究利用同源克隆技术获得抱茎独行菜TTG1基因cDNA开放阅读框（ORF）序列,命名为LpTTG1。序列分析表明,该基因ORF全长为1032 bp,编码343个氨基酸,含有WD40基序;qRT-PCR分析结果显示,该基因在抱茎独行菜各组织中均有表达,反映了该基因功能的多样性;免疫组织化学定位结果表明,LpTTG1在种子发育过程中内珠被和外珠被的表达水平变化与外珠被粘液质的合成过程相一致,推测该基因可能参与调控抱茎独行菜种皮的发育及粘液质的形成。将LpTTG1基因转化拟南芥,该基因的过量表达显著促进了粘液质合成途径下游基因AtMUM4在角果中的表达,表明该基因有可能参与粘液质合成途径调控,并促进下游产物MUM4的产生。然而,对LpTTG1转基因拟南芥与野生型植株表型的比较发现,两者种子形态及粘液质分泌与释放方式均无显著差异,这可能是因为抱茎独行菜种皮发育和粘液质形成是一个多基因调控的复杂过程,某一基因的过量表达也许不会引起明显的表型变化。     

甘肃南部7种高寒杜鹃生物量分配的异速生长关系

生物量分配模式影响着植物个体生长和繁殖到整个群落的质量和能量流动等所有层次的功能, 揭示高寒灌丛的生物量分配模式不仅可以掌握植物的生活史策略, 而且对理解灌丛碳汇不确定性具有重要意义。该研究以甘肃南部高山-亚高山区的常绿灌丛——杜鹃(Rhododendron spp.)灌丛的7个典型种为对象, 采用全株收获法研究了不同物种个体水平上各器官生物量的分配比例和异速生长关系。结果表明: 7种高寒杜鹃根、茎、叶生物量的分配平均比例为35.57%、45.61%和18.83%, 各器官生物量分配比例的物种差异显著; 7种高寒杜鹃的叶与茎、叶与根、茎与根以及地上生物量与地下生物量之间既有异速生长关系, 也有等速生长关系, 异速生长指数不完全支持生态代谢理论和小个体等速生长理论的参考值; 各器官异速生长关系的物种差异显著。结合最优分配理论和异速生长理论能更好地解释陇南山地7种高寒杜鹃生物量的变异及适应机制。     

温带半干旱地区不同管理水平下草坪杂草发生特征的比较研究

2000～2002年对呼和浩特地区不同草坪的杂草种类组成及其危害进行了调查,发现在3个不同管理水平的草坪中共出现80种杂草植物,其中管理水平较差、中等、较好的草坪分别有67种、37种和36种杂草,以菊科、豆科、禾本科植物占优势,不同草坪杂草群落的生活型谱有明显差异.根据危害度指数把草坪杂草分为极度、重度、中度、轻度、弱度危害5个等级,极度和重度危害杂草在管理水平较差、中等、较好的草坪中的种类比例分别为11.95%、21.63%和22.22%;在管理水平较差草坪中,极度危害杂草是早开堇菜和止血马唐,春季和秋季以早开堇菜的危害为主,夏季以止血马唐为主;在管理水平中等草坪中,极度危害杂草是赖草和止血马唐,赖草的高危害期在春秋季节,夏季以止血马唐为主要危害杂草;在管理水平较好的草坪中,极度危害杂草是鼠掌老鹳草、鹅绒委陵菜、赖草、欧亚旋复花,其中鼠掌老鹳草的危害度在整个生长季中占绝对优势.     

Vegetative propagation and sexual reproduction in the woodland understorey pseudo-annual Circaea lutetiana L.

On the forest floor of deciduous woodlands, relative light intensity gradually declines during the early growing season. The woodland understorey pseudo-annual Circaea lutetiana L. completes its life-cycle at the end of summer. These pseudo-annuals are clonal plants which survive the winter only as seeds and as hibernacles produced by the rhizome apices. In this paper, we asked several questions related to the life-history of C. lutetiana. It was found that shoot formation in early spring did not exhaust the old hibernacle. A trade-off between rhizome + hibernacle number and weight might be expected when plants grow under resource limitation. It was hypothesised that both number and weight of rhizomes and hibernacles will be affected by light availability. Since the effect of resource supply on the size number trade-off will depend on the developmental pattern of the rhizome system, rhizome development was studied as well. Soon after the shoots emerged, 1st order rhizomes were formed in May on the nodes of the old hibernacle. First-order rhizomes branched in June and 2nd order rhizomes (side-branches) were continuously produced throughout the growing season. The phenology and developmental rate of plants growing in different light treatments were plastic. On average 30% of rhizome biomass was formed during the vegetative phase, and rhizome and fruit production were only partly separated in time. The ratio of total rhizome biomass to total fruit biomass was not affected by light. Also flower bud removal did not lead to an increase in rhizome production, which suggests that division of biomass to both reproductive modes is rather rigid. The number of 1st order rhizomes was not affected by the light treatments. Under light limitation, both rhizome number and weight of single rhizomes were reduced. In contrast, fruit number, but not weight of single fruits, was limited.     

Acceptability of different species of Brassicaceae as hosts for the cabbage aphid

The probing and feeding behaviour of the cabbage aphid, Brevicoryne brassicae (L.), (Homoptera, Aphididae) was studied on several plant species that represented various levels of acceptability: Sinapis alba L. (a permanent host plant), Capsella bursa-pastoris (L.) Med., Thlaspi arvense L., Lunaria annua L., Erysimum cheiranthoides L. (accidental host plants), Vicia faba L. (a non-host plant), using the electrical penetration graph technique (EPG). B. brassicae on V. faba did not show any patterns related to penetration of phloem vessels. Stylet penetration was deterred on L. annua and E. cheiranthoides where non-penetration prevailed, the periods of sap ingestion were short or did not occur, the percentage of time spent in the phloem was consistently low (5–6%) and E1 salivation predominated. The pathway activities were not suppressed on C. bursa-pastoris and T. arvense and the aphids spent an average of 3 h in the phloem during the 8-h experiment. However, a considerable delay between finding and accepting the phloem and a substantial proportion of E1 salivation (20–30% of all phloem activities) indicated a deterrent factor in the sieve elements of these plants. Aphid probing and sap ingestion were rarely interrupted on S. alba. The results of this study suggest that the deterrent agents vary in activity and may hinder stylet penetration at different levels (epidermis, parenchymatous tissues and/or phloem elements), depending on the plant species.     

细叶百合的生物量和营养分配

 以栽培的2年生细叶百合（Lilium pumilum）为材料,于2000年的生长季从蕾期至种子成熟期进行6次取样,对其各器官生物量和氮、磷元素的配置进行了动态研究。结果表明,细叶百合虽然以种子繁殖为主,但在整个生长季用于生殖器官的生物量投资的比例并不很大,大量干物质分配到地下器官鳞茎中（平均为60.17%）;茎、叶的生物量分配比例仅次于鳞茎;雄蕊生物量分配比例明显高于雌蕊。在叶萌动及展叶初期植株全氮百分含量最高;从春季萌动至秋季果实成熟,叶中的氮呈逐渐递减的趋势;茎和生殖器官的全氮含量在蕾期最大;生殖器官与叶、鳞茎的全氮含量相关显著。磷在生殖器官的含量较高,这与磷在植物有性生殖过程中的重要作用相一致;生殖器官与茎的全磷含量相关显著。地下器官全氮、全磷随季节变化有增多的趋势;地上各器官全氮、全磷相关显著,随季节变化有明显减少的趋势。     

樟子松（Pinus svlvestris var. mongolica）人工群落生活史型谱

以东北林业大学植物园内的樟子松人工群落为研究对象,应用主成分分析方法在对群落内不同种的生活史型进行划分的基础上,对松科樟子松和白扦、槭树科糖槭、豆科紫穗槐、木犀科暴马丁香、蔷薇科毛果绣线菊和托盘、红豆杉科东北红豆杉、菊科飞廉和线叶旋覆花、禾本科扁穗草、罂粟科白屈菜、唇形科夏至草、十字花科荠菜14种植物生活史型及谱特征进行了定量化分析,以此为依据对群落演替和健康水平进行评价的可行性进行了探讨。结果发现此群落中主林层植物(樟子松和白扦)营养生长(Vegetationgrowth,V)达到46%,有性生长(Sexualgrowth,S)在35%,无性生长(Clonegrowth,C)约为19%;演替层植物(糖槭、紫穗槐、暴马丁香、毛果绣线菊、托盘和东北红豆杉)营养生长超过50%,无性生长略高于有性生长;草本层植物(飞廉、扁穗草、线叶旋覆花、白屈菜、夏至草和荠菜)营养生长接近于47%,有性生长只比营养生长少了4%,无性生长只占到11%。这些发现说明了主林层的生活史型是以营养生长为主的VS过渡生活史型,演替层植物应为V生活史型而草本植物为VS过渡类型。群落的生活史型是V0.49S0.33C0.18,属于VS过渡生活史型,在样地调查的14种植物中,生活史型大部分以营养为主,综合评价此群落处于以营养生长为主(49%)的健康群落水平,此群落中有性生长占总生活史型得分的33%,有向有性生长发展的趋势,但在一段时间内该群落应为稳定群落。     

大针茅草原地上生物量形成的规律与特点

大针茅草原能进行光合作用的时间为160—170天。地上生物量的季节生长曲线呈单峰型,适宜的收获期在8月份。地上生物量的增长与群落的高度增长呈明显相关(R=0.959)。立枯量于6月份开始出现,其增长规律与绿色量呈相反的趋势。刈割后的再生草量以春季(5月份)刈割后的产量最高。仲夏(7月份)刈割对草场生产力的威胁最大。群落产量结构的研究表明：5己于人cm以上可供牲畜采食的部分约占总产量的70—80％。     

Production and genetic analysis of partial hybrids in intertribal crosses between Brassica species (B. rapa, B. napus) and Capsella bursa-pastoris

Capsella bursa-pastoris (L.) Medic (2n = 4x = 32) is a natural double-low (erucic acid < 1%, glucosinolates < 30 micromol/g) germplasm and shows high degree of resistance to Sclerotinia sclerotiorum. Hybridizations were carried out between two Brassica species viz. B. rapa (2n = 20) and B. napus (2n = 38) as female and C. bursa-pastoris as male parent to introduce these desirable traits into cultivated Brassica species. Majority of F(1) plants resembled female parents in morphology and only a few expressed some characters of male parent, including the white petals. Based on cytological observation of somatic cells, the F(1) plants were classified into five types: two types from the cross with B. rapa, type I had 2n = 27-29; type II had 2n = 20; three types from the crosses with B. napus, type III was haploids with 2n = 19; type IV had 2n = 29; type V had 2n = 38. One to two chromosomes of C. bursa-pastoris were detected in pollen mother cells (PMCs) of type I plant by genomic in situ hybridization (GISH), together with chromosomal segments in ovary cells and PMCs of some F1 plants. Amplified fragment length polymorphism (AFLP) bands specific for the male parent, novel for two parents and absent bands in Brassica parents were generated in majority of F1 plants, even in Brassica-types and haploids, indicating the introgressions at various levels from C. bursa-pastoris and genomic alterations following hybridization. Some Brassica-type progeny plants had reduced contents of erucic acid and glucosinolates associated with improved resistance to S. sclerotiorum. The cytological and molecular mechanisms behind these results are discussed.     

Life cycle and growth ofPotamogeton crispus L. in a shallow pond,ojaga-ike

The life cycle and growth ofPotamogeton crispus L. were studied in a shallow pond, Ojaga-ike. With respect to the shoot elongation and seed and turion formations, the life cycle of this plant in the pond could be divided into following five stages: germination, inactive growth, active growth, reproductive and dormant stages. It was suggested that the plant showed these successive stages depending mainly upon water temperature. The turions germinated on the bottom in autumn when the water temperature fell below ca. 20 C. The plant showed hardly any growth during winter (December—early March) when the temperature was below 10 C. In the spring when the bottom water temperature rose to above 10 C (mid-March), the plant started to grow again and the shoot elongated rapidly at the rate of 4.2 cm day⁻¹ until the shoot apex reached the pond surface in late April. Both the increment of node number and the internodal elongation were associated with this rapid shoot growth. On 10 May (last sampling date), the mean values of shoot length, internodal length and the number of nodes estimated for 10 predominant plants were 238.2±5.6 cm, 7.1±0.8 cm and 34.9±4.0 cm, respectively. The turion formation and flowering occurred during the period from mid-April to mid-May when the surface water temperature ranged 19 and 22 C. The dry weight of a plant reached the maximum mean value of 1180 mg on 10 May. At its peak biomass, an individual plant produced 1–10 turions (5.5 on average) of which the mean individual turion dry weight was 53.2 mg. The turion dry weight accounted for ca. 42% of the total plant biomass m⁻² at that time.     

Anti-herbivory defense of two <Emphasis Type="Italic">Vicia</Emphasis> species with and without extrafloral nectaries

The effects of direct and indirect defenses differ among plant species, and the variation in the mode of plant defenses might reflect physiological and/or ecological constraints of each mode of defense related to the growth and reproduction of individual plant species. To evaluate the advantages and disadvantages of indirect ant-mediated defense via extrafloral nectaries (EFNs), we compared the herbivory pressure, leaf chemicals, vegetative growth, and reproduction between two species of vetches, Vicia sativa var. angustifolia (Reichard) Wahlenb (Leguminosae) with EFNs and V. hirsuta (L.) SF Gray without EFNs (or with very small EFNs). Indirect ant defense of V. sativa was not consistently reliable because of the low constancy of ant attraction. In addition, V. sativa was more vulnerable to attack by herbivores than V. hirsuta. The estimated total amount of sugars secreted by EFNs of V. sativa corresponded to 0.5% of total leaf biomass, and 0.07% of total plant biomass, indicating a low investment to the production of extrafloral nectar. Vicia sativa plants grew more rapidly than V. hirsuta plants during the reproductive stage. Therefore, we consider that V. sativa adopts the ant defense via EFNs in spite of its low reliability because the indirect ant defense supported by EFNs requires only low investment, allowing the plants to attain rapid growth in the early spring.     

The effect of urban ground cover on microclimate,growth and leaf gas exchange of oleander in Phoenix,Arizona

We assessed how small patches of contrasting urban ground cover [mesiscape (turf), xeriscape (gravel), concrete, and asphalt] altered the microclimate and performance of adjacent oleander (Nerium oleander L.) plants in Phoenix, Arizona during fall/winter (September–February) and spring/summer (March–September). Ground-cover and oleander canopy surface temperatures, canopy air temperatures and pot soil temperatures tended to be lowest in the mesiscape and highest in the asphalt and concrete. Canopy air vapor pressure deficits were lowest in the mesiscape and highest in the asphalt plot. Rates of net photosynthesis of all oleander plants were highest in October and May, and declined through mid-summer (June–July), when rates tended to be highest in the cooler mesiscape, particularly when water was limiting. During fall/winter, oleanders in the mesiscape produced 20% less biomass, 13% less leaf area, and had 12% lower relative growth rates (R_G) than those in the other ground covers. Lower nighttime temperatures in the mesiscape in December led to oleander frost damage. During spring/summer, oleanders in the mesiscape produced 11% more biomass, 16% more leaf area, and had 3% higher R_G than those in the other cover types. The effects of urban ground cover on oleander performance were season-specific; while oleander growth was greatest in the mesiscape during spring/summer, it was lowest during fall/winter and these plants experienced frost damage. Because all oleander plants produced >10 times as much biomass during the spring/summer, on an annual basis oleanders in the mesiscape produced 5–11% more biomass than plants in the warmer ground covers.